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declassifi ed 

By authority Socrotary of 

OCi 2U1960 

Defenae memo 2 August 1960 

ubbaby of congeess 

LC REGULATION: BEFORE SERVICING 
OR REPRODUCING ANY PART OF THIS 
DOCUMENT. ALL CLASSIFICATION 
MARKINGS MUST BE CANCELLED: 



SUMMARY TECHNICAL REPORT 
OF THE 

NATIONAL DEFENSE RESEARCH COMMITTEE 


DECLASSIFIED 
By authority Secretary of 

0C1 2 U 1960 

Defense memo 2 August 1960 
ffTWRAR Y OF CONGRESS 


markings must be CANCmji^ 




Manuscript and illustrations for this volume were prepared for 
publication by the Summary Reports Group of the Columbia 
University Division of War Research under contract OEMsr-1131 
with the Office of Scientific Research and Development. This vol- 
ume was printed and bound by the Columbia University Press. 

Distribution of the Summary Technical Report of NDRC has been 
made by the War and Navy Departments. Inquiries concerning the 
availability and distribution of the Summary Technical Report 
volumes and microfilmed and other reference material should be 
addressed to the War Department Library, Room lA-522, The 
Pentagon, Washington 25, D. C., or to the Office of Naval Re- 
search, Navy Department, Attention: Reports and Documents 
Section, Washington 25, D. C. 


Copy No. 

191 


This volume, like the seventy others of the Summary Technical 
Report of NDRC, has been written, edited, and printed under 
great pressure. Inevitably there are errors which have slipped past 
Division readers and proofreaders. There may be errors of fact not 
known at time of printing. The author has not been able to follow 
through his writing to the final page proof. 

Please report errors to: 

JOINT RESEARCH AND DEVELOPMENT BOARD 
PROGRAMS DIVISION (STR ERRATA) 

WASHINGTON 25, D. C. 

A master errata sheet will be compiled from these reports and sent 
to recipients of the volume. Your help will make this book more 
useful to other readers and will be of great value in preparing any 
revisions. 


SUMMARY TECHNICAL REPORT OF DIVISION 9, NDRC 


VOLUME 1 


CHEMICAL WARFARE AGENTS, 
AND RELATED CHEMICAL 
PRORLEMS 


Parts I— II DECLASSIFIED 

By authority Saeratary ot 

0C1 2 U 1960 

Defense memo 2 August 1960 
UBRABY^F CONGRESS 

OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT 
VANNEVAR BUSH, DIRECTOR 

NATIONAL DEFENSE RESEARCH COMMITTEE 
JAMES B. CONANT, CHAIRMAN 

DIVISION 9 LC REGULATION: BEFORE SERVICING 

w. R. KiRNER, CHIEF OR REPRODUCING ANY PART "HIS 
DOCUMENT, ALL CLASSIFICATION 
MARKINGS MUST BE CANCELLED'" 


WASHINGTON, D. C., 1946 


NATIONAL DEFENSE RESEARCH COMMITTEE 


9* 






^>4 
a ^ 


ei!^ 




iS»^ 


James B. Conant, Chairman 
Richard C. Tolman, Vice Chairman 
Roger Adams Army Representative ^ 

Frank B. Jewett Navy Representative ^ 

Karl T. Compton Commissioner of Patents ^ 

Irvin Stewart, Executive Secretary 


^Army representatives in order of service: 

Maj. Gen. G. V. Strong Col. L. A. Denson 

Maj. Gen. R. C. Moore Col. P. R. Faymonville 

Maj. Gen. C. C. Williams Brig. Gen. E. A. Regnier 

Brig. Gen. W. A. Wood, Jr. Col. M. M. Irvine 

IX! HEGULATTON- Qp 

OR RePSO^’’ , .^XION 

documein ..ancembbw on the organization 

The duties of the National Defense Research Committee 
were (1) to recommend to the Director of OSRD suitable 
projects and research programs on the instrumentalities of 
warfare, together with contract facilities for carrying out 
these projects and programs, and (2) to administer the tech- 
nical and scientific work of the contracts. More specifically, 

NDRC functioned by initiating research projects on re- 
quests from the Army or the Navy, or on requests from an 
allied government transmitted through the Liaison Office 
of OSRD, or on its own considered initiative as a result of 
the experience of its members. Proposals prepared by the 
Division, Panel, or Committee for research contracts for 
performance of the work involved in such projects were 
first reviewed by NDRC, and if approved, recommended to 
the Director of OSRD. Upon approval of a proposal by the 
Director, a contract permitting maximum flexibility of 
scientific effort was arranged. The business aspects of the 
contract, including such matters as materials, clearances, 
vouchers, patents, priorities, legal matters, and administra- 
tion of patent matters were handled by the Executive Sec- 
retary of OSRD. 

Originally NDRC administered its work through five 
divisions, each headed by one of the NDRC members. 

These were: 


^Navy representatives in order of service: 

Rear Adm. H. G. Bowen Rear Adm. J. A. Purer 

Capt. Lybrand P. Smith Rear Adm. A. H. Van Keuren 

Commodore H. A. Schade 
3 Commissioners of Patents in order of service: 

Conway P. Coe Casper W. Ooms 


OF NDRC 


In a reorganization in the fall of 1942, twenty-three ad- 
ministrative divisions, panels, or committees were created, 
each with a chief selected on the basis of his outstanding 
work in the particular field. The NDRC members then be- 
came a reviewing and advisory group to the Director of 
OSRD. The final organization was as follows: 


Division 

Division 

Division 

Division 

Division 

Division 

Division 

Division 

Division 


Division A — Armor and Ordnance 

Division B — Bombs, Fuels, Gases, & Chemical Problems 
Division C — Communication and Transportation 
Division D — Detection, Controls, and Instruments 
Division E — Patents and Inventions 


1 — Ballistic Research 

2 — Effects of Impact and Explosion 

3 — Rocket Ordnance 

4 — Ordnance Accessories 

5 — New Missiles 

6 — Sub-Surface Warfare 

7 — Fire Control 

8 — Explosives 

9 — Chemistry 

Division 10 — Absorbents and Aerosols 

Division 11 — Chemical Engineering 

Division 12 — Transportation 

Division 13 — Electrical Communication 

Division 14 — Radar 

Division 15 — Radio Coordination 

Division 16 — Optics and Camouflage 

Division 17 — Physics 

Division 18 — War Metallurgy 

Division 19 — Miscellaneous 

Applied Mathematics Panel 

Applied Psychology Panel 

Committee on Propagation 

Tropical Deterioration Administrative Committee 


IV 


Library of Congress 


460889 



201 5 



NAVAL ORDNANCE PLANS' 
iHdiemapolls. ladiaat. 
Library 

NDRC FOREWORD 


As EVENTS of the years preceding 1940 revealed 
jl\ more and more clearly the seriousness of the 
world situation, many scientists in this country came 
to realize the need of organizing scientific research for 
ser\dce in a national emergency. Recommendations 
which they made to the White House were given 
careful and sympathetic attention, and as a result the 
National Defense Research Committee (NDRC) was 
formed by Executive Order of the President in the 
summer of 1940. The members of NDRC, appointed 
by the President, were instructed to supplement the 
work of the Army and the Navy in the development 
of the instrumentalities of war. A year later, upon the 
establishment of the Office of Scientific Research and 
Development (OSRD) ,NDRC became one of its units. 

The Summary Technical Report of NDRC is a 
conscientious effort on the part of NDRC to summa- 
rize its work and to present it in a useful and perma- 
nent form. It comprises some seventy volumes broken 
into groups corresponding to the NDRC Divisions, 
Panels, and Committees. 

The Summary Technical Report of each Division, 
Panel, or Committee is an integral survey of the work 
of that group. The first volume of each group’s report 
contains a summary of the report, stating the prob- 
lems presented and the philosophy of attacking them, 
and summarizing the results of the research, develop- 
ment, and training activities undertaken. Some vol- 
umes may be “state of the art” treatises covering 
subjects to which various research groups have con- 
tributed information. Others may contain descrip- 
tions of devices developed in the laboratories. A 
master index of all these divisional, panel, and com- 
mittee reports which together constitute the Sum- 
mary Technical Report of NDRC is contained in a 
separate volume, which also includes the index of a 
microfilm record of pertinent technical laboratory re- 
ports and reference material. 

Some of the NDRC-sponsored researches which 
had been declassified by the end of 1945 were of 
sufficient popular interest that it was found desirable 
to report them in the form of monographs, such as 
the series on radar by Division 14 and the mono- 
graph on sampling inspection by the Applied Math- 
ematics Panel. Since the material treated in them is 
not duplicated in the Summary Technical Report of 
NDRC, the monographs are an important part of the 
story of these aspects of NDRC research. 


In contrast to the information on radar, which is of 
widespread interest and much of which is released to 
the public, the research on subsurface warfare is 
largely classified and is of general interest to a more 
restricted group. As a consequence, the report of Di- 
vision 6 is found almost entirely in its Summary 
Technical Report, which runs to over 20 volumes. 
The extent of the work of a division cannot therefore 
be judged solely by the number of volumes devoted 
to it in the Summary Technical Report of NDRC: 
account must be taken of the monographs and avail- 
able reports published elsewhere. 

Under the leadership of Walter R. Kirner as Chief, 
Division 9 conducted a broad program of research in 
the field of chemical warfare, both for offense and de- 
fense. Its principal responsibility was to ensure that 
this country would be prepared, should the enemy 
resort to the employment of poison gas as an offensive 
weapon. 

The staff of the Division prepared some two thou- 
sand chemical compounds, and tested them for tox- 
icity and vesicancy at a central laboratory. During 
the course of this program, a number of new chemical 
warfare agents were discovered which were potential 
deadly weapons. For defense, the Division contrib- 
uted to the development of methods and equipment 
for detecting and protecting against chemical agents, 
in vapor form or dissolved in water; important work 
was done in the development of an improved type of 
impregnated clothing. The Division also worked with 
the Committee on Medical Research in the problem 
of new anti-malarial agents, insecticides, and roden- 
ticides. 

The Summary Technical Report of Division 9, 
prepared under the direction of the Division Chief 
and authorized by him for publication, is a record of 
this work, a great deal of which constituted an insur- 
ance policy against a threat which did not material- 
ize. We can be thankful therefore, and we are grate- 
ful to the staff of Division 9 for its vital contributions 
in the field of chemical research. 

Vannevar Bush, Director 
Office of Scientific Research and Development 

J. B. CoNANT, Chairman 
National Defense Research Committee 


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FOREWORD 


D ivision 9, also known as the Chemistry Division, 
specialized mainly in chemical warfare prob- 
lems. Its activities were concerned with problems of 
both offense and defense. A large part of the program 
involved a search for new candidate chemical warfare 
agents particularly of the so-called persistent types. 
Nearly two thousand of such compounds were pre- 
pared. The most promising candidates were carried 
through the pilot plant so as to secure engineering 
data on their preparation and also to provide suf- 
ficient material for further evaluation in the labora- 
tory and in the field. The Division maintained a large 
central laboratory in which the candidate compounds 
were screened for toxicity and vesicancy. As a result 
of this program a number of new chemical warfare 
agents were discovered possessing the necessary tox- 
icity and other desirable properties. In addition, cer- 
tain improvements were suggested for the synthesis 
of some of the agents which had previously been 
standardized for chemical warfare use. 

On the defensive side. Division 9 made important 
contributions to the development of methods and 
equipment for the detection and analysis of chemical 
warfare agents in the vapor form or dissolved in 
water. Procedures were also devised for the removal 
of such agents from water. A great deal of effort was 
expended in the development of protective clothing. 
Division 9 investigators discovered stabilizers for the 
chemically-impregnated clothing manufactured by 
the Chemical Warfare Service, which greatly ex- 
tended its storage life. A new, so-called ‘‘aqueous im- 
pregnation process’^ for protective clothing was de- 
veloped which avoided shipment of large quantities 
of organic solvents to war theatres. Several kits were 
devised with which an individual or group of soldiers 
could impregnate their clothing in the event of an 
emergency. 

An intensive search was made for substitute im- 
pregnites to replace the one adopted by the Army. 
Certain of these new compounds, particularly several 
first prepared by Naval Research Laboratory inves- 
tigators, proved of outstanding value for use in pro- 
tective ointments. These agents were incorporated 
into the protective ointments standardized, man- 
ufactured, and distributed by the Army and Navy to 
personnel throughout the world, after their efficacy 
for this purpose had been discovered by Division 9 
investigators and methods developed for improving 


their synthesis and compounding them into oint- 
ments. 

A new approach to the problem of protective 
clothing was undertaken by Division 9 in its work on 
carbon-impregnated clothing following a lead fur- 
nished by the British. Three different methods of 
impregnating carbon into cloth were successfully de- 
veloped, two of which show unusual promise. The 
advantage possessed by carbon-impregnated fabrics 
over chemically-impregnated fabrics is that the for- 
mer will protect the wearer against all known persis- 
tent agents whereas the latter is limited to protection 
against agents of the mustard-gas type. 

Division 9 also carried on an extensive research 
program on the physiological mechanism of action of 
chemical warfare agents. The goal of this program 
was the discovery of effective methods of therapy to 
be used against gases which might be used by the 
enemy. While this did not result successfully in the 
case of mustard gas, a much clearer understanding 
was reached as to the mechanism by which this agent 
produces cell injury and vesication. The discovery of 
BAL by the British has made available a very ef- 
fective antidote against vesication by arsenical war 
gases of the Lewisite type. Toward the end of the 
war, when the effectiveness of the flame thrower was 
demonstrated in attacks on Japanese entrenched in 
caves and pill boxes, this program was extended to 
include a basic study of the physiological mechanism 
of action of heat on animals. 

Division 9 personnel participated in the field eval- 
uation of chemical warfare agents at all of the Chem- 
ical Warfare Service proving grounds. Practically all 
of the analytical work done at the Dugway Proving- 
Ground Mobile Field Unit Installation, Bushnell, 
Florida, was performed by Division 9 men on loan 
from its various contractors. Much of the analytical 
equipment used in these field tests was developed by 
Division 9 investigators. The important discovery 
made during these experiments under sub-tropical 
conditions was the considerably enhanced activity of 
mustard gas at high temperatures and high hu- 
midity. 

When it became evident that chemical warfare 
would not be initiated by the enemy or by the Allies, 
Division 9 shifted its emphasis from chemical war- 
fare problems to other urgent chemical problems. It 
cooperated with the Committee on Medical Research 


vii 


FOREWORD 


viii 


in a search for new, effective anti-malarial agents, 
insecticide formulations, insect repellents, and ro- 
denticides. The discovery of the new rodenticide 
“1080” was made jointly by investigators of Di- 
vision 9 and the Fish and Wildlife Service, Depart- 
ment of the Interior. 

Division 9, NDRC, was created in December 1942, 
at the time the Office of Scientific Research and De- 
velopment was organized and the NDRC reorgan- 
ized. Its predecessor Sections in Division B were 
first Sections A-2, A-3, and A-4 and later Sections 
B-3 and B-4. The early organization of the scien- 
tific work of these Sections had been most effectively 
carried outbj^ Drs. Roger x\dams, H. S. Gasser, W. C. 
Johnson, and C. S. Marvel. Their leadership was one 
of the important factors which contributed to the 
successful solution of many of the problems assigned 
to Division 9 by the Army and Navy. The other 
important factor was the ability, industry, and en- 
thusiasm of the official investigators and their asso- 
ciates and assistants in university and industrial 
laboratories in attacking the problems which were, 
in turn, assigned to them. Generous credit should 
also be given to the Division Members and Technical 
Aides who carried out the scientific administration of 
the many contracts which were under the aegis of 
Division 9. It is a pleasure to gratefully acknowledge 
here the assistance loyally rendered by all of these 
men in the laboratory accomplishments described in 


detail in the Division 9 Summary Technical Report, 
presented herewith. 

Particular expressions of gratitude are due the 
authors of the chapters which constitute the volumes 
summarizing the work of Division 9. Because of the 
policy adopted by this Division to summarize crit- 
ically not only the work of its own investigators, but 
also the contemporary work done in American Serv- 
ice laboratories and in the laboratories of our Allies, 
the task of writing was made considerably more 
difficult. However, it is believed that this overall 
summary will greatly add to the value of the volumes 
by giving as complete a picture as possible of present 
knowledge on each subject. 

Finally, special acknowledgment is made of the 
outstanding work done by Dr. Birdsey Renshaw, the 
editor of the Division 9 Summary Technical Report. 
He organized the report, coordinated the efforts of 
the authors of the respective chapters, wrote all or 
part of a considerable number of the chapters, and 
carefully edited each chapter as it was completed. 
This work has required his full time attention for well 
over a year during which his own desires to carry on 
laboratory work had to be postponed. However, now 
that the task is completed he will, I am sure, derive a 
great deal of satisfaction from having done it so well. 

W. R. Kirner 
Chief, Division 9 


PREFACE 


I T WAS THE CONSENSUS in Division 9 that the value 
of its Summary Technical Report, requested as a 
supplement to the numerous detailed reports already 
prepared and issued, would be greatly enhanced if an 
attempt were made not only to summarize the Divi- 
sion’s work but, in addition, to review critically the 
information available from other sources and relating 
to the subjects on which the Division had undertaken 
investigations. This seemed particularly desirable be- 
cause in most phases of the work the contributions of 
the Division and those of other agencies in the United 
States and British Commonwealth of Nations supple- 
mented and reciprocally influenced each other. Fur- 
thermore, the data on most of the pertinent subjects 
are scattered in numerous reports of various origins 
which in the future will be difficult to locate and 
evaluate. It seemed worthwhile, therefore, also to 
include a fairly complete Bibliography. 

This undertaking has been pursued, for the most 
part subsequent to the defeat of Japan, by men who 
had actively participated in the work of the Divi- 
sion. Most of the authors were burdened with other 
duties and have made considerable personal sacri- 
fices to write the summaries. Nevertheless, they have 
attempted conscientiously to present in useful form 
the significant facts and concepts that emerged rel- 
ative to their subjects during World War II. In so far 
as this aim has been attained, the reader will no 


doubt be willing to overlook stylistic and editorial 
heterogeneities. Unfortunately, it is inevitable that 
occasional omissions and errors must creep into a 
rapid compilation and assessment of as much mate- 
rial as is included in this Report. These the reader will 
accept with less equanimity, and for them the authors 
and the Editor ask forgiveness. 

By the time the Division closed in 1946 practically 
all of its work had been presented in detail in OSRD 
Formal Reports. These, therefore, comprise most of 
the references to the Division’s work that are given 
in the chapters and reproduced in microfilm. Most of 
the numerous informal and miscellaneous reports 
issued during the war were of an interim nature. They 
have been referred to and microfilmed only when 
they appeared to possess permanent value or in- 
cluded material not incorporated in OSRD Formal 
Reports. Among the informal reports that may ap- 
propriately be made a part of the accessible perma- 
nent record are the Section 9:4:1 (formerly B4-A) 
Informal Reports on Toxicity of Chemical Warfare 
Agents, and the Section 9:5:1 (formerly B6-C) In- 
formal Reports on Physiological Mechanisms of Chem- 
ical Warfare Agents. Both of these series are included 
in toto in microfilm. 

Birdsey Renshaw 
Editor 


IX 




CONTENTS 


CHAPTER PART I PAGE 

PREPARATION AND EVALUATION OF 
POTENTIAL CHEMICAL WARFARE AGENTS 

1 Resume of Agent Assessments 3 

2 Hydrogen Cyanide and Cyanogen Chloride 7 

3 Phosgene 17 

4 Disulfur Decafluoride 24 

5 Mustard Gas and Other Sulfur Mustards 30 

6 Nitrogen Mustards 59 

7 Arsenicals 83 

8 Aliphatic Nitrosocarbamates and Related Compounds . . 115 

9 Fluorophosphates and Other Phosphorus-Containing Com- 
pounds 131 

10 Methyl Fluoroacetate and Related Compounds . . . . 156 

11 Cadmium, Selenium, and the Carbonyls of Iron and Nickel 173 

12 Ricin 179 

13 Aromatic Carbamates 204 

14 Miscellaneous Compounds Prepared or Examined as 

Candidate Chemical Warfare Agents 246 

PART II 

SPECIAL PHYSIOLOGICAL AND 
TOXICOLOGICAL STUDIES 

15 The Assessment of Particulates as Chemical Warfare 

Agents 267 

16 Apparatus and Techniques Utilized in Toxicological 

Studies on Chemical Warfare Agents 278 

17 Physiological Mechanisms Concerned in the Production 

of Casualties by Exposure to Heat 303 

18 Miscellaneous Toxicological Studies 382 


^ For facility of handling, this Summary Technical Report of Division 9, Volume 1, has been 
bound and published in two sections. The first section contains Part I and Part II of Volume 9-1. 
Parts III-VI are found in the second section, together with the Glossary, Bibliography, OSRD 
Appointees, Contract Numbers, Project Numbers, and Index, all of which are applicable to 
both sections of Volume 9-1. 






v«» 


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PART 1 


PREPARATION AND EVALUATION OF POTENTIAL 
CHEMICAL WARFARE AGENTS 




Chapter 1 

RESUME OF AGENT ASSESSMENTS 

By Stanford Moore and Birdsey Renshaw 


1.1 INTRODUCTION 

R eviews of the information on the principal 
standard and potential chemical warfare agents 
are presented in Chapters 2 through 14. Summaries 
of the data on the standard agents — mustard gas, 
phosgene, hydrogen cyanide, and cyanogen chloride 
— are accompanied by reviews of other potential 
chemical warfare agents that were investigated 
during World War II. The reviews and bibliog- 
raphies are not limited to data obtained by the 
National Defense Research Committee [NDRC]. 
So far as possible all available information has been 
considered. 

The chapters deal primarily with the laboratory 
data on the chemical and toxicological properties of 
the agents. The technical aspects of the use of chem- 
ical warfare agents in the field have recently been 
summarized by the Project Coordination Staff. ^ 

In the discussions presented in this volume it is 
assumed that under certain conditions the use of each 
of the standard agents would be more effective from 
a military point of view than a similar expenditure of 
munitions charged with high explosive. ^ The experi- 
mental agents are assessed relative to the standard 
chemical agents on this basis. It has not been possible 
to take into consideration the recent development of 
the atomic bomb as a high-explosive weapon, the 
highly toxic radioactive gases encountered in the course 
of the research leading to the production of the atomic 
bomb, or the fnilitary potentialities of bacteriological 
warfare. For this reason the assessments made in the 
following chapters are limited in scope and cannot be 
considered cojnplete in the broadest sense. 

1.2 MAJOR TRENDS SINCE 

WORLD WAR I 

Mustard Gas Vapor 

From the laboratory and field test data obtained 
by the United States and the United Kingdom there 
developed during World War II a growing realization 
of the effectiveness of mustard gas vapor as a po- 
tential offensive weapon, particularly in tropical 
climates, in addition to its well-defined role as a de- 


fensive weapon. Emphasis in the field testing was 
placed on the thorough assessment of vapor dosages, 
as well as on the contact hazard presented by the 
contamination of various types of terrain with the 
liquid agent. It was demonstrated ^ that in hot 
weather relatively moderate expenditures of muni- 
tions would yield severely incapacitating vapor dos- 
ages within less than an hour, although the time of 
onset of the incapacitating symptoms was from 12 to 
24 hours after the brief exposure period. The effects 
were optimal on heavily vegetated tropical terrain of 
the t 3 ^pe characteristic of some of the combat areas 
in the war against Japan. 

Arsenical Vesicants 

At the close of World War I lewisite gained almost 
legendary fame as a potential vesicant agent. More 
recently thorough assessment of the arsenical vesi- 
cants has shown lewisite to possess few if any advan- 
tages over mustard gas and to have several properties 
which greatly reduce its efficiency. Its marked sus- 
ceptibility to hydrolysis, for example, lowers the 
vapor return from contaminated terrain and de- 
creases the effectiveness of the vesicant through 
clothing. The development of British anti-lewisite 
[BAL] as an antidote in arsenical poisoning also 
affected the assessment. Lewisite and related arseni- 
cal vesicants have, of recent date, received little con- 
sideration in the United States as potential offensive 
agents. 

Sternutators and Lacrimators 

Interest in sternutators and lacrimators has mark- 
edly decreased since World War 1. Particulate filters 
effective against sternutators are now standard 
equipment in the gas masks of all countries. In so 
far as harassment by chemical agents is a legitimate 
military objective, there is a tendency to prefer the 
use of agents that are potential^ lethal, particularly 
since British field trials under simulated combat con- 
ditions have demonstrated that the effectiveness of 
sternutators as harassing agents is limited. 

Use of Nonpersistent Agents 

As a means of attaining casualties by use of non- 
persistent gas against troops equipped with masks. 


3 


4 


RESUME OF AGENT ASSESSMENTS 


attention has been focused on surprise attacks with 
large bombs and on the possibilities of “breaking” 
the canister with high gas concentrations. Under 
favorable conditions of terrain and meteorology it 
has been found possible to attain with cyanogen 
chloride dosages that effectively penetrate the World 
War II models of German and Japanese canisters. 
The currently available United States canisters filled 
with ASC charcoal give effective protection against 
several times these dosages. 

High Explosive-Chemical Munitions 

German developments at the close of World War I 
pointed to the potentialities of high explosive-chem- 
ical shell. In 1921 Fries and West ^ noted with 
regard to mustard gas that: 

Due to the very slight concentrations ordinarily encoun- 
tered in the field, resulting from a very slow rate of evapora- 
tion, the death rate is very low, probably under 1 per cent 
among the Americans gassed with mustard during the war. 

If, on the other hand, the gas be widely and very finely dis- 
persed by a heavy charge of explosive in the shell, the gas is 
very deadly. In such cases the injured breathe in minute parti- 
cles of the liquid and thus get hundreds of times the amount of 
gas that would be inhaled as vapor. This so-called “high ex- 
plosive mustard gas shell” was a German development in the 
very last months of the war. Its effects were great enough to 
make it certain that in the future large numbers of these shell 
will be used. 

The Germans followed this lead in their develop- 
mental work during World War II. They apparently 
favored chargings that could be dispersed from mu- 
nitions not readily distinguishable by sound from 
similar high-explosive weapons and that would give 
relatively odorless vapor and droplet clouds. For this 
purpose the Germans filled shell and bombs with the 
nitrogen mustard, (jS-chloroe thy 1) amine (HNS), 

and with the so-called Trilons (see Chapters 6 and 9). 
From the available data it would appear that the use 
of munitions of this type in admixture with high ex- 
plosive munitions would have been an effective 
means of employing chemical agents. A similar em- 
ployment of 4.2-inch mortar shell charged with a 
nitrogen mustard was considered by the United 
States Chemical Warfare Service and would have re- 
ceived further attention in the event of the outbreak 
of gas warfare. It would appear that the Germans 
placed greater emphasis on this method of using gas 
and had obtained more data than the United States 
and the United Kingdom on the properties of high 
explosive-chemical shell and on the relative suitabil- 
ities of various chargings for these munitions. Field 
assessments of the lethal effectiveness of particulate 


clouds of ricin and of the clouds obtained from in- 
cendiary weapons containing cadmium were ob- 
tained by the United States and the United King- 
dom and also bear on this problem. It is probable 
that future research in the United States will aug- 
ment the data on the Trilons and on the effectiveness 
of particulate clouds of high toxicity. 

Toxicological Testing 

There is a general realization of the need for con- 
tinued toxicological screening on a broad basis of 
newly synthesized organic chemicals. The German 
Trilons were synthesized in the course of a search by 
industry for new insecticides. Routine testing on ani- 
mals brought them immediately into consideration 
for military uses. For a routine survey program the 
use of intravenous injections is simpler than determi- 
nation of toxicity by inhalation and suffices to detect 
compounds which merit further study. 

Experience gained during World War II has em- 
phasized the importance of obtaining an approxima- 
tion of the toxicity of agents for the human species. 
This point becomes evident from the studies on di- 
sulfur decafluoride, the fluorophosphates, the fluoro- 
acetates, and cadmium oxide. The various animal 
species showed such widely varying susceptibilities 
to the agents that estimates of the order of magni- 
tude of their effectiveness against man could not be 
made without collateral data. The fundamental 
physiological and biochemical studies leading to a 
closer definition of the lethal dose of hydrogen cya- 
nide for man (see Chapter 2) provide another exam- 
ple. Thus the possibility of wide species variations 
merits consideration at the outset of detailed study. 
In screening by intravenous injection, the use of 
several species at an early stage is essential to the 
adequate assessment of the potentialities of a new 
compound. 

1.3 BRIEF SUMMARY OF ASSESSMENTS 
OF COMPOUNDS OF PRINCIPAL INTEREST 

Hydrogen Cyanide and Cyanogen Chloride 

For the task of production of immediate deaths by 
the attainment of effective dosages in less time than 
is required for masking, hydrogen cyanide (AC) was 
considered from the toxicological point of view to be 
the best available agent. Its competitors which arose 
during World War II are the almost equally quick- 
acting but much less volatile fluorophosphates and 
related compounds, one of which the Germans de- 


SECRET 


SUMMARY OF ASSESSMENTS OF COMPOUNDS 


5 


cided to put into production for use in high explosive- 
chemical shell and bombs. The tendency of AC to 
flash in some munitions is a disadvantage which has 
not been overcome. 

In the United States cyanogen chloride (CK) was 
second choice to AC in the task cited in the preceding 
paragraph and was also considered for the special 
task of penetrating early World War II models of 
Japanese and German canisters under highly favor- 
able conditions of terrain and meteorology. 

Phosgene 

Phosgene (CG) was the principal nonpersistent 
gas of World War I and was the standard nonper- 
sistent chemical filling for United States bombs and 
mortar shell at the outbreak of World War II. When 
delayed physiological effects are acceptable, CG has 
been considered the most economical standard non- 
persistent agent for the production of casualties by 
attainment of effective dosages in less time than is 
required to mask and for the production of casualties 
among unprotected personnel. 

Disulfur Decafluoride 

The difficulty and expense of manufacture of 
disulfur decafluoride (Z) on a large scale have pre- 
vented it from being seriously considered as a com- 
petitor for CG. The agent possesses the important 
advantage of relative lack of odor, and its physical 
properties are satisfactory. However, its toxicity 
shows considerable species variation and the lethal 
dosage for man cannot at present be estimated with 
a degree of accuracy sufficient for a close toxicologi- 
cal comparison with CG. 

Sulfur Mustards 

No competitors for 6fs(j3-chloroethyl) sulfide (H) 
were developed in the course of the study of a wide 
variety of analogs after World War I and during 
World War II. The search for a more volatile (i.e., 
less persistent) vesicant agent led only to compounds 
with markedly inferior toxicological potency. The 
high vesicancy of some of the less volatile analogs 
was studied quantitatively, however, and found to be 
sufficient to merit the addition to H of l,2-6fs(/3-chlo- 
roethylthio) ethane (Q) or 6f5(jS-chloroethylthioethyl) 
ether (T) when long persistency of contact hazard on 
terrain or materiel is desired. 

Nitrogen Mustards 

The principal item of military significance that 


emerged from the study of the nitrogen mustards was 
the possible use of (jS-chloroe thy 1) amine (HNS) 
as a filling for high explosive-chemical shell. For most 
other purposes where a vesicant agent could be em- 
ployed to advantage H was shown to have properties 
superior to those of the nitrogen mustards. 

Arsenicals 

The thorough assessment of the arsenical vesi- 
cants indicates that lewisite (L) and analogs are in 
general inferior to the sulfur mustards. Subsequent 
to the introduction of silver impregnation for canister 
fillings arsine has not seriously been considered as a 
potential agent. Relatively little military value is 
currently attached to the use of irritant arsenical 
smokes. 

Aliphatic Nitrosocarbamates 

Studies on methyl N-(j8-chloroethyl)-N-nitroso- 
carbamate (KB-16) and related structures showed 
this series of compounds to possess a high degree of 
toxicity. As an eye-injurant KB-16 is approximately 
as potent as H and is less readily detected by odor. 
As a vesicant, however, it is markedly inferior to H. 
It has also been found to be insufficiently stable for 
storage in munitions. 

Fluorophosphates and Trilons 

In 1941 British investigators initiated studies on 
the fluorophosphates as potential war gases. The 
most effective members of the series studied by the 
United States and the United Kingdom were di- 
methyl fluorophosphate (PF-1) and diisopropyl 
fluorophosphate (PF-3). PF-1 and PF-3 do not pos- 
sess sufficiently high toxicities by inhalation to have 
an advantage over the standard chemical warfare 
agents. Limited data are available on the related 
agents (Trilons) discovered by the Germans during 
World War II. The member of the series which they 
placed in production was ethyl dimethylamidocyano- 
phosphate (MCE). Difficulty in synthesis prevented 
the Germans from producing isopropyl methane- 
fluorophosphonate (MFI) , which apparently possesses 
superior chemical and toxicological properties. It is 
clear that the Trilons are more toxic than PF-1 or 
PF-3. They are quick-killing agents possessing a 
powerful parasympathomimetic action. The Trilons 
would seem to be the one new group of chemical 
agents discovered during World War H that merit 
a position among the standard agents. 


SECRET 


6 


RESUME OF AGENT ASSESSMENTS 


Fluoroacetates and Related Compounds 

Reports that methyl fluoroacetate (MFA) is highly 
toxic were received from Polish investigators by the 
British in 1942. This class of compounds received 
careful chemical and toxicological study in the United 
Kingdom and the United States. The wide species 
variation in toxicity pointed to the need for a reason- 
ably accurate estimate of the lethal dose for the 
human species before an assessment could be made. 
If these agents had proved to be as toxic for man as 
for some animal species they would have been in a 
class with the Trilons. However, data becoming 
available in 1944 made it possible to estimate that 
the toxicity for man is low and to conclude that MFA 
and related compounds do not possess the general 
utility of the currently standardized gases. They re- 
main a subject of military concern because of their 
possible use as food or water poisons. In addition, as 
a by-product of the chemical warfare research, so- 
dium fluoroacetate has been demonstrated to have 
many practical properties as a rodenticide. 

Cadmium Oxide; Metal Carbonyls 

Cadmium is considered a promising material for 
addition to incendiary munitions if toxicity as well 
as fire is desired. The highly toxic cadmium oxide 
which results from the combustion of the incendiary 
mixes is odorless and relatively nonirritating. 

Iron and nickel carbonyls have been considered as 
possible additions to flame thrower fuels if increased 
toxicity of the combustion products is an objective. 


Ricin 

Ricin (W) is a protein of very high toxicity. The 
absence of odor and the complexity of the detection 
problem in the field would render it more insidious 
than any standard United States or British chemical 
warfare agent. As a result of progress made during 
World War II on the preparation of ricin, it is poten- 
tially available in relatively large quantities. Im- 
proved munitions for its dispersal as a particulate 
cloud are required before the toxicity of the agent 
can be adequately utilized. Comparison of the ef- 
fectiveness of the initial dust cloud of ricin with that 
of the initial cloud from the German Trilons would 
be indicated. The casualty-producing effects from 
exposure to ricin, however, are delayed, like those of 
phosgene poisoning, whereas incapacitation and 
death from the Trilons is produced relatively rapidly. 

Aromatic Carbamates 

Research by the United Kingdom and the United 
States during World War II has made available in 
pilot plant quantities a series of crystalline aromatic 
carbamates possessing extremely high toxicity. By 
subcutaneous injection the most effective members 
of the series are comparable in potency with the 
German Trilons. For some purposes the fact that 
they are crystalline solids is advantageous. For dis- 
persion by high explosive- chemical shell the Trilons 
have the advantage of being liquids. The possible 
utilization of aromatic carbamates may rest prima- 
rily on the availability of suitable munitions. 


SECRET 


Chapter 2 

HYDROGEN CYANIDE AND CYANOGEN CHLORIDE 

By Stanford Moore and Marshall Gates 


2.1 INTRODUCTION 

A RELATIVELY large amount of open and classified 
literature has accumulated on the properties of 
hydrocyanic acid and cyanogen chloride and on their 
behavior when liberated from munitions. To survey 
the complete subject is beyond the scope of this chap- 
ter. The sections which follow are designed to show 
the relationship of the data obtained by NDRC Di- 
vision 9 to the body of knowledge on these agents. 

Hydrocyanic acid (AC) was adopted by the United 
States as a standard filling for frangible grenades in 
July 1942 and as a substitute standard filling for 
1,000-lb bombs in October 1943. From the toxico- 
logical standpoint this agent was one of the standards 
for comparison in the evaluation of potential new gas 
warfare agents under investigation by NDRC during 
World War II. 

Cyanogen chloride (CK) was standardized as a 
quick-acting nonpersistent gas filling for 1,000-lb 
and 500-lb bombs in October 1943 and for 4.2-inch 
mortar shell in July 1945. 

For the task of production of immediate deaths by 
the attainment of effective dosages in less time than 
is required for masking, AC is considered from the 
toxicological standpoint to be the best agent avail- 
able.'*^ Its competitors are the almost equally 
quick-acting but much less volatile fluorophosphates 
and related compounds, one of which was put into 
production by Germany (Chapter 9). The tendency 
of AC to flash in some standard munitions is a dis- 
advantage which has not been overcome. 

The primary interest in CK arose from the demon- 
stration by NDRC Division 10 that CK showed 
greater promise for the penetration of World War II 
models of Japanese and German canisters than any 
other readily available agent. The protection af- 
forded by Japanese canisters in particular was so 
low that there was promise of attaining lethal pene- 
tration of enemy masks from moderate expenditures 
on jungle terrain or heavily wooded areas. CK can 
be satisfactorily stabilized for storage and is non- 


® Based on information available to Division 9 of the Na- 
tional Defense Research Committee [NDRC] as of November 
1, 1945. 


inflammable. It is also second choice to AC in the 
task cited in the preceding paragraph. 

In this chapter reference will be made to the pri- 
mary chemical and toxicological basis on which the 
standardization of these agents rested. 

2.2 PREPARATION AND PROPERTIES 

2.2.1 Preparation 

Hydrocyanic acid (AC) has long been available on 
a commercial scale. The cost of production at the 
present time is about five times that for phosgene. 
Cyanogen chloride (CK) was produced by the French 
in World War I and on a small scale in the United 
States prior to World War II. Larger scale produc- 
tion, by a process based upon the chlorination of 
aqueous hydrocyanic acid, was undertaken in 1944 
at the plant in Azusa, California. 

2.2.2 Physical Properties 


The physical properties which have the most direct 
bearing on the effectiveness of these agents as war 
gases are the following: 



AC 

CK 

Density (liquid) g/ml at 20 C 

0.69 

1.19 

Boiling point, C 

25.7 

12.6 

Freezing point, C 

-13.4 

-7.0 

Heat of vaporization, cal/g 

210 

135 

Vapor density, relative to air 

0.93 

2.0 


The liquid density affects the amount of agent 
which can be loaded per munition; the freezing point 
is of importance in cold weather or on high-altitude 
bombing missions; the boiling point influences the 
rate of evaporation of the liquid agent; the heat of 
vaporization also influences the rate of evaporation 
and determines the cooling of the air produced by 
evaporation of the agent from a functioned munition. 
The cooling effect in turn influences the stability of 
the gas cloud produced, since the cooler layer of air 
tends to remain longer near ground level. Prior to the 
performance of adequate field studies on these agents 
it was considered that, since AC has a lower vapor 
density than that of air, the persistence of its clouds 
should be much less than the persistence of those 


SECRET 


7 


8 


HYDROGEN CYANIDE AND CYANOGEN CHLORIDE 


from CK and CG, which are heavier than air. Actu- 
ally, clouds of AC and CK show essentially the same 
persistence and downwind travel.^^ Considered in 
conjunction with the cooling effect arising from the 
latent heat of vaporization and with the meteoro- 
logical factors governing the turbulence of the air, 
the data show that the vapor density of the gas does 
not play so important a role as was first thought. 

The boiling points of AC and CK are sufficiently 
low so that the agents vaporize completely within a 
few seconds after dispersal in droplet form from 
bursting munitions. 

2.2.3 Stability of AC 

Pure AC is unstable on storage, ultimately decom- 
posing with explosive violence, but the presence of 
small amounts of mineral acids, particularly phos- 
phoric acid, produces marked stabilization. Present 
Chemical Warfare Service specifications call for the 
addition of 0.07 per cent orthophosphoric acid and 
0.3 per cent sulfur dioxide as stabilizers, and surveil- 
lance tests have demonstrated that AC stabilized 
according to these specifications and charged into 
clean bombs is stable when held at 150 F for 60 to 90 
days.^®’^^’'^^ Powdered copper, used by the Japanese 
as a stabilizer in AC munitions, has also shown prom- 
ise as a stabilizer, particularly in the presence of steel, 
which gradually exhausts the phosphoric acid sta- 
bilizer.^*^-'^-®-’’ 

The tendency of AC to inflame on functioning of 
munitions constitutes the principal disadvantage of 
AC as a chemical warfare agent. In field trials with 
500-lb and 1,000-lb bombs an appreciable percentage 
of the munitions flashed in some instances. Extensive 
efforts have been made to overcome or minimize this 
tendency both by changing the bursters and by al- 
tering the composition of the charging. The addition 
of aliphatic hydrocarbons in C 5 -C 6 range originally 
appeared promising and led to field tests 

on them and also on gasoline as flash-inhibiting dil- 
uents. The early trials indicated that flashing 
could be reduced by the addition of 5 per cent of 
70-octane gasoline to AC in M47A2 100-lb bombs, 
and in larger bombs, but subsequent work indicated 
that the addition of gasoline to AC does not satisfac- 
torily prevent flashing if the mixture is allowed to 
stand for 20 days or longer after the addition of the 
gasoline.^^^^ No solution of the problem of flashing of 
bombs charged with AC which would keep the per 
cent flashing consistently below 10 per cent, for ex- 


ample, has been obtained. The fact that in some 
series of trials no flashing is encountered indicates 
that the problem may not be an insoluble one. 

2.2.4 Stability of CK 

Pure CK, and also the CK produced technically in 
this country, may be kept in glass for long periods 
even at elevated tempera tu res. ^ Stability be- 

comes a problem only on storage in metals. Investi- 
gations have proceeded along three lines: ( 1 ) the 
determination of the effect of storage in contact with 
metals, particularly steel, on the stability of CK, 
( 2 ) determination of the effects of the impurities en- 
countered in technical CK on its storage life in steel, 
and (3) minimization of the effects of contact with 
metal and of impurities by the addition of a stabilizer. 

The chemical change involved in the polymeriza- 
tion of CK is largely one of trimerization to cyanuric 
chloride ^^’^ 8,59 13 ^^ other reactions, the products of 
which were undetected until recently, also occur to a 
minor extent.^ It was recognized many years ago 
that acids, particularly hydrochloric acid, promote 
the polymerization to a marked degree. The-addition 
of 2 per cent of hydrochloric acid is sufficient to pro- 
duce explosive polymerization,^^ but the amount of 
hydrochloric acid likely to be present in technical CK 
is harmful only if appreciable water is also present.^* 
The presence of chlorine and hydrogen cyanide were 
also held to be deleterious by early workers.^* 
Chlorine is still regarded as harmful,^* although 
there is some evidence that it is less critical than 
formerly supposed. However, it presents no problem 
since it is well controlled in the manufacturing proc- 
ess. The amount of AC present can be varied within 
wide limits without affecting the stability of CK.'^-^® 

Work on the stabilization of CK was undertaken 
in 1942 by NDRC Division 10. The early work was 
confined to experiments on pure CK stored in glass 
at room temperatures.^ The harmful effects of chlo- 
rine and gross quantities of acid were observed, and 
it was noted that cyanuric chloride had no effect on 
the rate of polymerization. Later work, however, 
has shown that this is true only in the absence of 
steel and also that water, observed in this early 
work to have little effect even in gross quantities, is 
actually very harmful to CK stored in steel. Mag- 
nesium oxide effectively stabilizes CK against the 
harmful effect of chlorine. Canadian workers have 
observed that magnesium oxide also protects against 
excess acidity but it does not appear to meet the 


SECRET 


PREPARATION AND PROPERTIES 


9 


requirements for a good stabilizer.'*^ A number of 
other substances were examined for their effects on 
the stability of CK, but the surveillance tests, done 
at room temperature over relatively short periods 
(i.e., 2 to 6 weeks), were not sufficiently rigorous to 
give information useful in predicting the stability of 
munitions charged CK. 

In 1943 the study of the stabilization of CK was 
intensified by NDRC Division 10, and much funda- 
mental chemistry relating to CK, in particular to 
those reactions taking place during the storage of 
crude CK, w^as elucidated. 

A detailed description of this work is given else- 
whereA The more important results are enumerated 
here. 

1. Although the earlier work showing the general 
deleterious effect of acids and of chlorine on the sta- 
bility of CK was confirmed, the special position of 
water, particularly in the presence of steel, was recog- 
nized.^^* Thus the stability of CK in the presence 
of steel decreases with increasing original water con- 
tent, whereas no such correlation is shown with acid 
or with hydrogen cyanide. Hydrogen chloride, AC, 
and ammonium chloride all cause little polymeriza- 
tion if moisture is absent.^^-* 

2. A number of stabilizers were proposed and 
tested. They were suggested before the importance 
of iron salts and of water was realized, and the ra- 
tionale for most of them was removal of acid. Propy- 
lene oxide, first proposed as a stabilizer by the 
American Cyanamid Corporation,*^ and ethylene 
oxide absorb acid even when dry and were at first 
believed to be promising stabilizers. Later work 
showed them to be definitely harmful.'* Dimethyl- 
cyanamide, an end product of the reaction of CK with 
trimethylamine, a reaction analogous to von Braun’s 
“bromcyan” degradation, absorbs tw'o moles of 
acid.^® It was suggested for trial as a stabilizer by the 
fact that no polymerization occurs during its forma- 
tion from CK and trimethylamine.^* How^ever, the 
stabilizing effect appears to be due primarily to the 
production of a coating on the steel, and, if the sam- 
ple is agitated during surveillance, no stabilization 
results.'* Likewise, it was possible to demonstrate a 
stabilizing effect due to the formation of the complex 
(HCN) 2 - (HCOa only if a considerable excess of AC 
was present, and then the stabilization was slight.^® 

Parallel to this work and supplementing it, the 
Chemical Warfare Service carried on surveillance 


*» See the Summary Technical Report of Division 10. 


tests in munitions charged CK, originally on CK 
produced by the American Cyanamid Corporation 
at Warners, New Jersey, and later on CK produced 
at Azusa, California, as w^ell. The results of these 
surveillance tests, wLich w^ere carried out for 30, 60, 
and 90 days and ultimately for longer periods at 
65 C, in general confirmed the conclusions reached 
in laboratory scale tests as to the effects produced by 
the usual impurities in technical CK. Good quality 
CK was showm to have adequate stability when 
charged into clean munitions. *^’*^’*^ These surveil- 
lance tests also afforded realistic opportunities for 
the evaluation of stabilizers developed in laboratory 
scale tests. 

The NDRC Division 9 group which undertook a 
search for stabilizers for CK during 1944 observed 
the beneficial effects of a number of inorganic sub- 
stances including sodium pyrophosphate, calcium 
oxide, and potassium fluoride. In the interest of ex- 
pediency it proved necessary to carry out surveil- 
lance tests on these stabilizers at 100 C and 125 C.*® 
The applicability of the results of such accelerated 
tests to stability at lower temperatures was a matter 
of detailed study. All groups engaged in laboratory 
scale surveillance tests on CK ultimately adopted 
these temperatures. The rate of polymerization of 
CK increases by the usual factor of 2 per 10-degree 
rise in temperature (determinations have given 1.7 
to 2.5) and the character of the polymerization ap- 
pears to be the same at 125 C as at 75 C.®*^ However, 
ammonium chloride in CK produces acid in surveil- 
lance at 100 C but not at 65 C,*^** and it is possible 
that surveillance at higher temperatures may lead 
to an underestimate of stability at lower temper- 
atures.*'^^’®’* 

The effectiveness of sodium pyrophosphate, the 
best of the above-mentioned group, and of calcium 
oxide is much greater than that of organic stabilizers 
such as ethylene and propylene oxides and the dial- 
kylcyanamides, which in spite of early promise were 
shown to be definitely deleterious.*® Marked im- 
provement in the storage qualities of even poor grade 
CK is obtained with sodium pyrophosphate. For CK 
of average quality, 2 per cent sodium pyrophosphate 
is adequate, although 5 per cent has been recom- 
mended and adopted to make certain that poor 
batches receive adequate stabilization.'* With this 
concentration of stabilizer, CK of any grade has 
better keeping qualities in the presence of steel than 
has the same CK stored in glass but unstabilized.'* 
Poor quality CK has a short life even in glass, how^- 


SECRET 


10 


HYDROGEN CYANIDE AND CYANOGEN CHLORIDE 



Table 1 

. Surveillance of CK (Azusa Lot 686) for 60 days at 65 C.^ 




Na2P-207 


Acidity 

Soluble 



Munition 

(%) 

Density 

as HCl 

residue Iron 

H 2 O 

HCN 

M78 bomb 

0 



Polymerized after 60 days 



M78 bomb 

5 

1.204 

0.017 

0.06 0.001 

0.051 

1.94 


ever, and to be suitable for charging into munitions 
CK should have a solidification time in glass at 125 C 
of at least 10 days.^-^^"’^’® This implies low values for 
soluble iron and for water content. 

An example of the behavior of actual munitions 
charged CK when stabilized with sodium pyrophos- 
phate is given in Table 1.^^ 

The stability of CK samples which have already 
been stored in steel without a stabilizer is markedly 
improved by the addition of 5 per cent sodium pyro- 
phosphate, and CK thus treated has at least as long 
a life in steel as when stored in glass without a 
stabilizer.*® 

There appears to be some correlation between the 
stability of a sample of CK and its soluble iron con- 
tent.*® A corresponding correlation between water 
content and stability appears at low values of water 
content *®’^2® but is much less marked for higher 
values, the critical value being about 0.2 per cent 
water.*® However, the susceptibility to stabilization 
by sodium pyrophosphate is strikingly dependent on 
water content, as illustrated by the data of Table 2.^* 

Although only limited data are available, the pres- 
ence in CK of potassium pyrophosphate and pre- 
sumably of sodium pyrophosphate appears to have 
little effect on its content of water, iron, acid, or 
hydrogen cyanide, although the rate of trimer forma- 
tion is reduced. Over a 9-day period less than 0.002 
per cent potassium pyrophosphate dissolves in 
CK.^ 

Since the stabilizing action of sodium pyrophos- 
phate is probably a surface phenomenon the particle 
size is important. “Kiln run” or “granular” sodium 


pyrophosphate is unsuitable, and it is necessary to 
include in the specifications a clause, easily met by 
the commercial “powder” grade, specifying the 
proper screening characteristics. A suitable set of 
specifications, readily met by commercial material, 
has been suggested.*® 

Little or no heat effect is produced when 5 per cent 
sodium pyrophosphate is added to CK with as much 
as 0.3 per cent water content, whereas the addition 
of calcium oxide to similar material may produce a 
rise in temperature of 4 C. The addition of calcium 
oxide to CK of higher water content may produce 
dangerous heat effects."^ 

The recommendations made in 1943^^’^* as to the 
limits of impurities which should be allowed in CK 
for charging chemical warfare munitions (i.e., HCl, 
0.005 per cent; water, 0.005 per cent; HCN, 0.02 per 
cent; and chlorine, none) proved to be unnecessarily 
stringent. 

The present U. S. Army specifications for CK 
stored in 1-ton containers call for water, 0.5 per cent; 
hydrogen cyanide, 3 per cent; soluble residue, 0.02 
per cent; chlorine, 0.005 per cent; acid (as HCl), 
0.024 per cent; iron, 0.02 per cent; and CK assay, 
96 per cent minimum.*^ 

Five per cent sodium pyrophosphate is added to 
the container prior to the addition of the CK. The 
specifications for 4.2-inch mortar shell charged CK 
also require the addition of 5 per cent sodium pyro- 
phosphate to the shell prior to charging.** 

CK is noninflammable and there is thus no prob- 
lem of ignition of the charging by bursting munitions 
as in the case of AC. 


Table 2. Effect of water on stabilization of CK by sodium pyrophosphate.^ 


Conditions 

Water 

content 

Days for complete 
solidification 

Stabilization 
in days 

CK 

0.03% 

40, 40 


CK 4- 0.3 g steel (control) 

CK + 0.3 g steel -b 5% Na 2 P 207 


7, 7 

>209, >209 

>202, >202 

CK 

0.23% 

11, 12 

CK 4- 0.3 g steel (control) 

CK 4- 0.3 g steel 4-5% Na 2 P 207 


7, 7 

89, 89 

82, 82 

CK 

0.53% 

8, 12 


CK 4- 0.3 g steel (control) 

CK 4- 0.3 g steel 4-5% Na 2 P 207 


3, 6 

15, 15 

9, 9 


SECRET 


TOXICOLOGY 


11 


2.2.5 Detection and Analysis 

Chemical methods for the detection of AC and CK 

are outlined in Chapter 34. Methods of analysis have 
been developed for the assay of plant run products 
with special reference to the impurities which may 
lower the stability of the agents on storage. The dis- 
cussion of titrimeters in Chapter 37 includes the de- 
scription of continuous recording instruments for 
AC and CK utilizing potentiometric titrations. 
NDRC Division 10 has developed recording instru- 
ments utilizing conductivity measurements and these 
instruments have been widely employed in the de- 
termination of concentrations of AC and CK in the 
field test programs. 

AC is detectable by odor at about 0.03 g/1 (i.e., 
30 mg/1)^^ on the average, although some men may 
lack almost completely the ability to detect the odor 
of cyanide. CK is readily detectable at about 0.02 
mg/1 both by its immediate lacrimatory effect and 
its irritant effect on the nasal passages. At concen- 
trations as low as 0.002 mg/1 the eye irritation is 
noticeable by some observers in less than 3 minutes. 

2.2.6 Canister Penetration 

The dosages of AC and CK required for lethal 
penetration of captured German and Japanese can- 
isters '^2.43 (1941-42 models) are about the same but 
the advantage lies with CK because of the higher 
dosages attained in the field.® The higher liquid 
density of CK, which permits heavier bomb load- 
ings, contributes to the higher dosages obtained per 
bomb. Lethal penetration of Japanese canisters by 
CK was obtained at dosages of 50,000 to 200,000 
mg min/m^ at normal breathing rates. U. S. canisters 
filled with ASC charcoal give protection against sev- 
eral times these dosages. Field trials have demon- 
strated that dosages of CK in the range of 50,000 to 

200.000 can be attained by feasible munition ex- 
penditures under favorable conditions of terrain and 
meteorology.'^^ 

2.3 TOXICOLOGY 

2.3.1 Toxicity 

For the production of casualties among men prior 
to adjustment of the mask, the toxicity of the agent 
when breathed for 30 seconds, or perhaps 2 minutes 
in the case of sleeping troops, is the important char- 
acteristic. Against personnel without gas masks (e.g., 
in city populations) the toxicity of the agent over 

® See the Summary Technical Report of NDRC Division 10. 


longer periods is of importance. The toxicity over 
longer periods also comes into consideration in study 
of the physiological action of the concentrations pen- 
etrating canisters. 

Ideally, the toxicity for man is the information de- 
sired. The data to be summarized in this chapter are 
based primarily on measurements of the action of the 
gases on various animal species and conclusions on 
the values of the agents are drawn therefrom. It 
should be noted, however, that in 1944 a thorough 
analysis of the problem of the indirect estimation of 
toxicities of AC, CK, and CG for man was made 
jointly by the Toxicological Research Laboratory of 
the Medical Division, Chemical Warfare Service, 
and the NDRC-University of Chicago Toxicity 
Laboratory.^® For each of the three agents research 
programs were drawn up designed to provide in- 
directly the answer to the question of the concentra- 
tions required to cause death in man. Such an 
approach in the case of cyanide appeared particularly 
promising since certain basic data on the effect of 
cyanide on man are known from the open literature 
on the clinical use of sodium cyanide. The work on 
these programs is still in progress. 

The detailed considerations of the probable effects 
of the three agents on man have led to a fuller under- 
standing of the action of these nonpersistent gases 
and to more adequate interpretations of munitions 
trials. From the summary of the above-mentioned 
status report the sections on AC and CK are quoted 
to give the principles which enter into the attempt 
to make an indirect determination of the toxicities 
for man. 

The purpose of this review was to define the laboratory ex- 
periments still required to reduce to a minimum the error in 
estimate of the concentrations of AC, CK, and CG required to 
cause death in man at different times of exposure. 

A consideration of the tasks proposed for AC, CK, and CG 
discloses that concentrations of each agent lethal to man in 
0.5, 1, 2, 10, 30, and 60 minutes are desired. 

AC is known to be detoxified by animals and man. CK is 
detoxified by animals and so is presumably detoxified by man. 

AC is detoxified by man at a rate of ca. 0.017 mg/kg/min 
when injected*^ slowly This does not differ markedly from 
the rates at which it is detoxified by lower animals.®® 

CK is detoxified by the rabbit, dog, and goat at rates of 
0.03-0.06; 0.02-0.04; and 0.03-0.1 mg/kg/min respectively 
depending on the rate of injection.^^-^^a-b Arguing by analogy 
with AC, man presumably will detoxify CK at a rate within 
these limits (0.02-0.1 mg/kg/min). 


The experiments were made with NaCN, which upon in- 
jection into the tissues at about pH 7 yields HCN almost 
quantitatively. 


SECRET 


12 


HYDROGEN CYANIDE AND CYANOGEN CHLORIDE 


We have estimated that the LD50 of AC for man is ca. 1.1 
mg/kg. This estimate rests on: 

a. The LD-m of AC® for six species of animals which 
indicates that the various species are not different in suscep- 
tibility, thus implying that man will fall in the same range. 

b. Amounts of cyanide found in the tissues of humans com- 
mitting suicide by taking cyanides 

c. The fact that the LD50 of AC bears an apparently con- 
stant ratio to the rate of detoxication of AC in various species. 

The LDso’s of CK for the rabbit, dog and goat are 3.15, 3.30, 
and 2.97 mg/kg respectively.-' By analogy with AC man is 
probably equally susceptible. 

Such evidence as is available indicates ^ that AC is equally 
toxic by inhalation or intravenous injection.®*' It is held in this 
review that this is also true for CK. 

The minute volumes of different species of animals are stim- 
ulated differently by AC, 7-fold in the dog, 2-3-fold in the 
rabbit, and 1.5-fold in the guinea pig.®** These volumes are suf- 
ficient to allow inhalation of an amount of AC approximately 
equal to the LDso of AC for the several species. 

Man’s respiration is stimulated 7 to 10-fold by intrave- 
nously injected AC in single doses of ca. 0.055 mg/kg or more 
(estimated from reference 56).« The duration of such stimula- 
tion is ca. 20 seconds.** When infused slowly the percent stim- 
ulation is less (2-3-fold) but is longer maintained. 

If CK is not more toxic by inhalation than by intravenous 
injection, then it too must stimulate the respiration of some 
species to allow the inhalation of a lethal dose. CK is known 
to stimulate the respiration of the dog (after causing apnea be- 
cause of its irritancy).®®® 

No satisfactory evidence is available to indicate that dif- 
ferences in the susceptibility of various species to AC and CK 
cannot be explained on the basis of difference in minute vol- 
umes in the presence of the gas, and the value of the intra- 
venously injected LD50.* 

It is suggested that the toxicity of agents like AC and CK 
can be described as a first approximation by the formula 

VaC - Dt = K 

in which 

V = total volume of air breathed in 1/kg 
a = the fraction of inhaled gas absorbed 
C = concentration in mg/1 
D = rate of detoxication in mg/kg/min 


® Intravenous LDso’s of AC in mg /kg (unanesthetized 
animals): dog 1.34, cat 0.81, monkey 1.30, rabbit 0.66, guinea 
pig 1.43, rat 0.81, and mouse 0.99. For anesthetized goats an 
LD50 of 0.66 has been obtained.^^ There are indications that 
the intravenous for anesthetized and unanesthetized 

animals are the same in some species but may not be iden- 
tical in others.®-® 

f Later confirmed for dogs by the development of apparatus 
for direct measurement ®®® but found not to hold for rabbits,®®^ 
where the LD-yo by way of the lung pi'oves to be about half of 
the intravenous LD^o. 

K This value for the respiratory stimulating dosage of in- 
jected NaCN has been checked in more recent studies on 
measurement of the velocity of blood flow in man.®' 

*• Lesser stimulation but longer duration have been observed 
in legal executions with .\C (reference 16 and later unpublished 
data). 

i See exception in Note e. 


t = time in minutes from first entrance of the sub- 
stance into the body (roughly, the exposure 
time) 

K = the lethal dose in mg/kg 

The source of greatest doubt in estimating concentrations 
of AC and CK required to cause death in man from the above 
equation is the question of man’s minute volume in the pres- 
ence of the substance. 

On the above basis, if a 70-kg man breathed 25 1 
of air during a 1-minute exposure to AC, the volume 
breathed per kilogram would be 25/70 = 0.36 1. If 
70 per cent of the inhaled AC is absorbed by the 
lungs, as experimentally determined for the dog,^^‘' 
the equation can be solved for the necessary lethal 
concentration of AC: 

0.36 X 0.7C - 0.017 X 1 = 1.1 

and 

C = 4.4 mg/1. 

In this instance for the 1-minute exposure the L{Ct)i,o 
would be 4,400 mg min/m^. As has been pointed out, 
however, a meaningful estimate of man’s minute 
volume in the presence of the gas is not readily made. 
It is upon earlier calculations of this type by British 
investigators that the internationally agreed esti- 
mates of 5,000 and 11,000 mg min/m^ for the L{Ct)^oS 
of AC and CK are based. As guides for use in mu- 
nitions assessments the estimates have proved useful. 

An alternative approach for use in determination 
of munitions requirements, developed from these 
data, places the emphasis on attainment of the mini- 
mum respiratory stimulating dosage rather than on 
the L{Ct)^Q. This approach is based upon the fact 
that upon detection of AC a man will try to hold his 
breath long enough to adjust the mask. If the amount 
of gas which he inhales in the first breath is sufficient 
to stimulate the respiration, the probability of his 
receiving a lethal dose prior to adjustment of the 
mask is increased. 

For a sedentary individual the volume inhaled per 
breath is about 0.6 1. If the first breath is to insure 
stimulation of respiration it should yield absorption 
of about 0.055 X 70 = 3.9 mg of AC per 70-kg man. 
If the absorption coefficient is 0.7, the concentration 
of gas to be aimed at in the gas cloud would be 
3.9/ (0.6 X 0.7) = 9.3 mg/l. 

It can be seen from this analysis that the predic- 
tion of the toxicity of AC for man, if feasible, is a 
problem requiring knowledge of the mechanism of 
the action of AC, its inherent toxicity per kilogram 
of body weight in different species, its influence on 
the rate and volume of respiration, the per cent of 


SECRET 


TOXICOLOGY 


13 


Table 3. L{Ct)toS of AC for different species. 

Species 

Exposure time 
(min) 

L{Ct),o 

(mg min/m^) 
or suggested value 
where number of 
animals is small 

A = anal. cone. 

N = nom. cone. 

Number of 
animals 
used 

Reference 

Mouse 

1 

3 

400 

A 

25 

11 


1 

3 

500 

A 

44 

2 


1 

900 

A 

44 

2 


1 

600 

A 

50 

11 


2 

1,300 

A 

95 

6a 


2 

1,280 

A 

260 

15 


2 

1,160 

N 

160 

6f 


2 

1,280 

N 

160 

6f 


2 

1,320 

N 

80 

6f 


3 

1,100 

A 

30 

11 


10 

2,300 

A 

300 

12 


30 

5,250 

N 


6g 


30 

5,600 

A 

180 

15 

Rat 

1 

3 

800 

A 

24 

2 


1 

1,550 

N 

76 

6h 


2 

2,200 

A 

100 

23 


3 

1,800 

A 

18 

11 

Guinea pig 

1 

3 

2,500 

A 

28 

2 


1 

2,100 

N 

60 

6h 

Rabbit 

1 

850 

N 

32 

6e 


10 

3,200 

A 

21 

11 

Cat 

1 

850 

N 

30 

6e 

Monkey 

1 

1,700 

N 

10 

6e 

Dog 

1 

3 

800 

A 

30 

11 


1 

700 

N 

24 

6e 


1 

700 

A 

26 

11 


3 

1,000 

A 

26 

11 

Goat 

1 

3 

1,300 

A 

20 

31 


2 

2,200 

A 

18 

24 


the gas which is absorbed by the lungs, and its rate 
of detoxication. The outlay of research required to 
gain an approach to the actual toxicity for the human 
species is an effort which has been attempted only 
for a few agents of primary importance. In general 
the screening of possible new war gases has rested on 
the routine determination of the for vari- 

ous animal species. Most of the toxicological conclu- 
sions on new agents have had to rest on comparison 
of animal L{Ct)s,o’s, combined with qualitative evalu- 
ation of the effects of the different agents on man. 

The data on the L{Ct)^o values of AC and CK for 
different species are summarized in Tables 3 and 4. 
Where the number of animals used in the determina- 
tion is small, the LiCt)^^ is only an approximation. 
In these tables the values which have a fairly sub- 
stantial experimental basis have been included. The 
tables include World War I and World War II data. 
A fuller tabulation is given elsewhere. 

A comparison of the L{Ct)hQS of AC and CK for 
different species is given in Table 5 for exposure 
times of 1 to 2 minutes. Since the density of the gas 


governs the weight of filling per bomb of given vol- 
ume, the last column in the table represents the effi- 
ciency in terms of munition chargings. From Table 5 
it is seen that for most of the species AC is several 
times as effective as CK in short exposure periods. 
For long exposures the ratio of the toxi cities ap- 
proaches a value close to the inverse ratio of the 
cyanide radical contents of the two gases. 

The course of respiration of goats during exposures 
to AC and CK has been studied in detail at Dugway 
Proving Ground. During exposure to AC for 2 min- 
utes, respiration was normal for the first few sec- 
onds.^^^ At concentrations above 2.5 mg/1 the time 
of onset of stimulation of respiration was 10 to 
20 seconds after the start of the exposure. The dura- 
tion of stimulation was 30 to 100 seconds and was 
followed by a depression of respiration setting in at 
40 to 150 seconds. In similar experiments with CK 
at concentrations above 2 mg/1 respiration is irregu- 
lar and depressed during the first 30 to 80 seconds.^^® 
The breath is not actually held, however, as in the 
case of goats exposed to phosgene Fol- 


SECRET 


14 HYDROGEN CYANIDE AND CYANOGEN CHLORIDE 


Table 4. L(Ct)ioS of CK for different species. 



L{Ct)io 







(mg min/m^) 
or suggested value 

A = anal. cone. 

Number of 




Exposure time 

where number of 


animals 



Species 

(min) 

animals is small 

N = nom. cone. 

used 


Reference 

Mouse 

1 

2 

3,000 

A 

50 


44 


1 

4,550 

N 

160 


6b 



3,640 

A 





1 

4,200 

A 

29 


44 


2 

5,600 

N 

120 


6f 


2 

5,300 

N 

100 


3 


2 

6,200 

A 

180 


14 


2 

3,600 

A 

70 


44 


3 

4,200 

A 

40 


44 


10 

7,900 

N 

200 


3 


10 

7,500 

A 

160 


14 


30 

13,500 

N 

180 


3 


30 

13,800 

A 

140 


14 

Rat 

1 

13,000 

N 

35 


3 


2 

9,400 

A 

30 


44 


3 

5,400 

A 

20 


44 


7i 

6,300 

A 

18 


10 


30 

9,000 

A 

16 


10 

Guinea pig 

1 

15,000 

N 

35 


3 

2 

7,000 

A 

30 


44 


2^ 

5,500 

A 

16 


10 


7h 

9,000 

A 

13 


10 


30 

17,000 

A 

13 


10 

Rabbit 

1 

13,000 

N 

10 


3 


2 

8,000 

A 

24 


44 


7h 

6,000 

A 

23 


10 


30 

17,000 

A 

20 


10 

Cat 

1 

6,000 

N 

10 


3 

Monkey 

1 

4,400 

N 

20 


3 

Dog 

1 

3,800 

N 

26 


3 


3 

4,200 

N 

18 


3 


7i 

4,500 

A 

26 


10 


10 

5,000 

N 

26 


3 


30 

6,000 

N 

14 


3 

Goat 

2 

3,600 

A 

30 


25 

lowing the period of depression, ther 

e is a stimulated 

this later period of depression is 

followed by com- 

phase of 40 to 90 seconds’ duration and this result is 

plete respiratory paralysis, usually 

within a few 

in accord with the 

conversion of CK to AC in the 

minutes, in those animals receiving lethal dosages 

body, as described 

in Section 2.3.3. There follows a 

and by gradual 

return to normal 

in 

those receiving 

variable period during which the respiration again 

sublethal quantities of the agents. 



falls below the basal rate. With both AC and CK 

Since CK yields AC in the body, a 50/50 mixture 


Table 5. Comparison of L{Ct)ioS of AC and CK for short exposure times. 




Exposure 

time L(Ct) 5 o of CK 

L(C05o of CK Density of AC 

LiCt)oo of AC Density of CK 

Species 

(min) 

L{Ct),o of AC 

Goat 

2 

1.6 


0.9 



Monkey 

1 

2.6 


1.5 



Mouse 

1 

4.0 


2.3 



Dog 

1 

5.4 


3.1 



Cat 

1 

7.0 


4.1 



Guinea pig 

1 

7.1 


4.1 



Rat 

1 

8.4 


4.9 



Rabbit 

1 

15.3 


8.9 




SECRET 


TOXICOLOGY 


15 


of AC and CK should show a toxicity which is a 
function of the combined effect of the cyanide con- 
tributions from both agents. In a series of determina- 
tions of the toxicities for mice of AC diluted with 
increasing percentages of CK, the 2-minute L{Ct)^Q 
was 1,250 for pure AC, 1,880 for 50/50 AC-CK, and 
5,400 for pure CK.®^ Calculated on the basis of cya- 
nide radical content the values are, respectively, 
1,200, 1,300, and 2,300. Part of the lower effective- 
ness of CK on a cyanide content basis is to be ac- 
counted for by the tendency of the irritant vapors of 
CK to depress respu’ation during the first part of the 
exposure period. That there is reinforcement between 
the two agents is evidenced by the fact that the 50/50 
mixture is essentially as toxic as pure AC on a cya- 
nide radical basis. 

AC vapor is absorbed slowly through the skin. 
Experiments on body exposure during which the 
animals breathed uncontaminated air indicated that 
mice were killed at 10-minute Ct’s of about 200,000 
mg min/m*, cats at 500,000, and dogs at 1, 000,000. ^ 
The order of the sensitivity in these tests is to be ex- 
pected on the basis of an increase in the required Ct 
with decrease in the ratio of body surface to body 
weight. The results serve to indicate that for man the 
required Ct is of such a magnitude that it does have 
significance in the consideration of AC as chemical 
warfare agent. 

The irritancy of CK vapor to the human skin has 
been noted by personnel engaged in field tests with 
this agent. In a series of chamber experiments under 
controlled conditions groups of men wearing masks 
were exposed to several concentrations of CK.'*^ Un- 
der hot and humid conditions the irritation, primarily 
in the genital region, became severe at 2.0 mg/1. 
Under temperate conditions similar effects were ob- 
tained at about 3.6 mg/1. The irritation, although 
severe, is transient and does not persist after re- 
moval from the CK-containing atmosphere. 

The LDso’s of AC and CK by intravenous injection 
have already been cited. When administered orally 
or by stomach tube, the rate of absorption of the 
agents from the digestive tract affects the In 

orally administered doses of NaCN sufficient to kill 
dogs within less than 10 minutes, as much as three- 
fourths of the administered cyanide is found in the 
gastrointestinal tract after death. In dosages yield- 
ing later deaths the per cent absorption is higher. 
Calculated on the basis of absorbed HCN, the LD^q 
orally administered is not significantly different from 
the intravenous value. The LD^ds for ocular and for 


nasal administration of AC in cats are also found to 
be close to the intravenous value. The LAo of CK 
administered in aqueous solution by stomach tube 
has been found to be approximately 6 mg/kg with 
deaths occurring at about 30 minutes.^® 

2.3.2 Pathology 

In animals dying from acute cyanide poisoning 
pathological examination shows evidence of marked 
tissue anoxia. Hemorrhages are most apparent in the 
thymus glands. ^ Pathological studies from World 
War I and from World War II indicate that residual 
lesions from AC are significant only in the case of 
animals receiving an exposure in a narrow range just 
below the minimal lethal dose, resulting in irrevers- 
ible injury to the more susceptible nervous tissue but 
failing to cause acute respiratory paralysis and death 
of the animal. Nearly all animals recovering from 
sublethal doses do not experience significant tissue 
anoxia and are free from any demonstrable after- 
effects. In the animals showing residual neurological 
damage the principal pathological changes are noted 
in the cerebrum and the cerebellum. ^ 

Residual paralysis following CK exposures is sim- 
ilar to that obtained with AC and is observed more 
frequently in dogs than in other species.®® In addition 
CK has a local irritant effect on lung tissue. In occa- 
sional instances the lung irritation can lead to pul- 
monary edema,2®’‘‘^ which may be important from 
the therapeutic standpoint. From the offensive 
standpoint the pathological results show that the 
immediate paralyzant effect of CK greatly over- 
shadows its other effects.'*'* 

Mice appear to be more resistant than dogs to 
lung irritation from CK. Mice surviving 35 exposures 
to nearly lethal dosages of CK showed no gross 
pathological lesions in the lungs.®"* 

2.3.3 Physiological Mechanism 

Hydrocyanic acid exerts its lethal action through 
inhibition of cellular respiration producing an as- 
phyxia leading to death. The agent causes a tem- 
porary increase in respiratory volume as a result of 
action on the carotid body; if the carotid body is re- 
moved, only respiratory depression is obtained. The 
therapeutic value of methemoglobin is a result of its 
strong affinity for cyanide, in competition with cyto- 
chrome oxidase, yielding a nonionized and nontoxic 
combination. 

In extension of the basic information on the mech- 


SECRET 


16 


HYDROGEN CYANIDE AND CYANOGEN CHLORIDE 


anism of action of AC, the competition for cyanide 
between methemoglobin and cytochrome oxidase 
has been demonstrated in vivoP^ The therapeutic 
value of methemoglobinemia induced by nitrates 
and by p-aminopropiophenone has been thoroughly 
studied by Medical Division, Chemical Warfare 
Service, and by the Office of Scientific Research and 
Development [OSRD] Committee on Medical Re- 
search. C 3 ^anide is detoxified by gradual excretion 
as thiocyanate and the therapeutic value of thiosul- 
fate has been further investigated. From the prac- 
tical standpoint the deaths from exposure to gaseous 
AC are rapid and under battlefield conditions there 
would be few opportunities to apply therapeutic 
procedures of this type in time to be of value. The 
production of methemoglobinemia among large 
groups of troops as a protective measure prior to 
possible exposure has been considered but is not a 
practical procedure in the field and would reduce the 
efficiency of all troops thus treated.^® 

It has been demonstrated that cyanogen chloride 
is converted to hydrocyanic acid in the body and 
exerts its lethal effect as AC. Some of its other toxi- 
cological properties such as irritancy to the nasal 
passages and local action on lung tissue are char- 
acteristics of CK itself. The similarities in the actions 
of CK and AC were pointed out by British investi- 
gators in the reporting of the conversion of CK to 
AC in whole blood in a matter of seconds. Blood 
serum alone does not accomplish the conversion. 
The reaction is not a simple one and proceeds in two 
stages.'^® CK reacts with hemoglobin to give a com- 
pound which in the presence of reduced glutathione 
yields AC. In connection with the mechanism of 
the first stage it has been demonstrated that CK is 
capable of reacting with both amino groups 
and sulfhydryl groups of amino acids and pro- 
teins.® 

Following the British work the observations were 


extended to additional animal species, to blood in 
vitro and in vivo, and to human blood. The conver- 
sion is not quantitative. The maximum conversion 
by human red cells was 86 per cent and the average 
was considerably lower than this value. About 75 per 
cent conversion has been found in vivo in the rabbit. 
No free CK is present, however. The fate of the frac- 
tion which does not appear as HCN has not been 
determined. 

Although a slow combination of CK with met- 
hemoglobin can be demonstrated when the agent is 
present in great excess, the slowness of this combi- 
nation compared with the rate of the conversion 
reaction to AC makes it unlikely that the combi- 
nation of CK with iron compounds such as met- 
hemoglobin has any significance in vivo.^^^ Induced 
methemoglobinemia is effective therapeutically 
against CK 32a, 33b agreement with the data on 
conversion to AC. 

2.4 EVALUATION AS WAR GASES 

For the task of production of immediate deaths by 
the attainment of effective dosages in less time than 
is required for masking, AC is considered from the 
toxicological standpoint to be the best agent avail- 
able.'*^ Its competitors are the almost equally 
quick-acting but very much less volatile fluorophos- 
phates and analogs, one of which was put into pro- 
duction by the Germans (Chapter 9). The tendency 
of AC to flash in some standard munitions is a dis- 
advantage which has not been overcome. 

For the task of penetration of World War II mod- 
els of German and Japanese canisters under favorable 
conditions of terrain and meteorology, CK was the 
most suitable agent. It can be satisfactorily stabi- 
lized and is nonin flammable. It is also second 
choice to AC in the task cited in the preceding 
paragraph. 


SECRET 


Chapter 3 

PHOSGENE^ 

By Sta7iford Moore and Marshall Gates 


3.1 INTRODUCTION 

P HOSGENE (CG) was the principal nonpersistent 
gas of World War I and was the standard non- 
persistent gas filling for United States bombs and 
mortar shell at the outbreak of World War II. 
Throughout World War II the stocks of CG were 
maintained at a much higher level than those of AC 
and CK, which were later standardized as quick- 
acting nonpersistent agents. When delayed physiolog- 
ical effects are acceptable, CG has been considered 
the most economical standard nonpersistent agent 
for the production of casualties by attainment 
of effective dosages in less time than is required to 
mask or for production of casualties among unpro- 
tected personnel. 

This chapter summarizes primarily the recent ad- 
vances in the information on the toxicological action 
of CG. Data on the chemistry and toxicology of 
diphosgene and carbonyl chlorofluoride are also in- 
cluded. These two agents parallel CG in toxic action 
but have not been considered to possess any major 
advantages over CG as chemical warfare agents. 

3.2 PREPARATION AND PROPERTIES 

3.2.1 Preparation and Stability 

CG has been prepared industrially for many years 
by the direct combination of carbon monoxide and 
chlorine under the catalytic influence of activated 
carbon. The product is stable and long experience 
has shown that CG can be stored indefinitely in iron 
and steel containers in the absence of moisture. 

3.2.2 Physical Properties 

The physical properties of CG which have the 
most direct bearing on the use of this gas as a war- 
fare agent are listed below (see Chapter 2 for proper- 


ties of AC and CK). 

Density (liquid) g/ml at 20 C 1.38 

Boiling point, C 8.3 

Freezing point, C —104 

Heat of vaporization, cal/g 60 

Vapor density, relative to air 3.5 


* Based on information available to Division 9 of the 
National Defense Research Committee [NDRC] as of 
December 1, 1945. 


CG possesses several advantages over AC and CK 
in its physical properties. It has a higher liquid den- 
sity and a lower boiling point than AC or CK. The 
freezing point of CG is so low that the agent will re- 
main liquid at any temperature to be encountered in 
operations. From the standpoint of gas cloud be- 
havior, the effect of the lower heat of vaporization 
of CG is offset in part by its greater vapor density. 
Field trials show little difference between the travel 
of CG clouds and that of CK clouds. 

3.2.3 Detection and Analysis 

Chemical methods for the detection and analysis 

of CG are outlined in Chapter 34 of this volume.^ 
The median detectable concentration by odor is 
given as 0.006 mg/l.^^ 

3.2.4 Canister Penetration 

The dosage of CG required for lethal penetration 
of the more recent models of German, Japanese, or 
Allied canisters is 500,000 to 1,000,000 mg min/m^ 
under conditions favorable for penetration and as 
much as twice these figures for humidified canisters 
at low breathing rates.^^ In general, dosages in this 
range are beyond those which can be obtained over a 
significant portion of a target area by feasible ex- 
penditures. Thus both Allied and enemy canisters 
provide good protection against this agent. 

3.3 TOXICOLOGY 

3.3.1 Toxicity 

CG exerts its lethal action by injury of the lung 
tissue in contrast to AC and CK, which are systemic 
poisons. The rate of detoxification is so low that it 
comes into consideration only in the study of de- 
fensive measures against long exposures to trace con- 
centrations in manufacturing plants. An approach to 
the problem of the toxicity of CG for man differs 
from that applied to the systemic poisons. The dif- 
ferences in the susceptibility of the various species 
to CG have been attributed to the following factors 
which govern the extent of injury to the lung tissue: 

See also the Summary Technical Report of Division 10. 


SECRET 


17 


18 


PHOSGENE 


Table 1. L(C05o’s of CG for different species. 

Species 

Exposure time 
(min) 

L(Ct)io 
(mg min/m®) 
or suggested value 
where number of 
animals is small 

.4 = anal. cone. 

N = nom. cone. 

X umber of 
animals 
used 

Reference 

Mouse 

1 

3,450 

N 

240 

9 


1 

6,300* 

N 

300 

9 


2 

4,700 

A 

180 

22 


3 

1,950 

X 

200 

9 


10 

1,800 

N 

220 

9 


10 

3,800 

A 

100 

20 


20 

2,000 

N 

280 

9 


30 

3,400 

A 

160 

22 

Rat 

1 

6,500 

N 

24 

9 


30 

1,400 

N 

32 

17 

Guinea pig 

1 

2,800 

N 

28 

9 


30 

1,300-2,200 

N 

30 

17 

Rabbit 

30 

1,000 

X 

30 

17 

Monkey 

1 

600-1,000 

X 

13 

9 


5 

625 

A 

21 

39 


10 

750 

A 

25 

39 


30 

1,000 

X 

14 

17 

Dog 

0.5 

8,100 

A 

28 

18 


1 

8,400 

A 

28 

18 


1 

7,000 

N 

9 

9 


3 

4,500 

A 

29 

18 


5 

4,500 

X 

16 

9 


5 

4,250 

A 

29 

18 


20 

4,200 

X 

19 

9 

Goat 

2 

4,600 

A 

14 

28 


2 

6,500 

A 

72 

27 

Horse 

ca. 10 

ca. 10,000 

A 

23 

34 

* Determination 

on Jackson strain of mice. 

Other OSRD data are on 

Car worth male mice. 




1. Differences in the amount breathed during ex- 
posure. 

2. Differences in the depth of inhalation and the 
size and shape of the upper respiratory tract, leading 
to a relatively greater absorption of agent in the 
upper respiratory tracts of the smaller species. 

3. Minor differences in tissue susceptibility. 

4. Differences in resistance to death from the pro- 
longed anoxia resulting from pulmonarj^ edema, such 
differences being knowm to be present even within a 
given species with variations in nutritional state and 
general health of the animals. 

The factors involved in the toxic action of CG are 
such that the differences in the sensitivities of dif- 
ferent species to this agent are more difficult to in- 
terpret than in the study of AC and CK. L{Ct)f^ 
measurements for different species are summarized 
in Table 1. The relative L{Ct)^QS of CG, AC, and CK 
are given in Table 2. 

The data show the effect of a depression of respira- 
tion during short exposures to CG.^® The 1-minute 
L{Ct)^^s are in most cases several times the 10- or 
30-minute figures. In the case of the goat it was not 


possible to determine the L{Ct)^Q for a 30-second ex- 
posure time since the animals frequently held their 
breath during the complete period in the presence of 
high concentrations. 27 The depression of respiration 
in this species was actually characterized by breath 
holding and was more marked than the action of CK, 
which under similar conditions induced depressed 
respiration but not complete cessation. This reflex 
respiratory inhibition evoked by CG has also been 
studied in detail in the dog.® At concentrations higher 
than 7 mg/1 the first inhalation of the phosgenized 
atmosphere caused total cessation of respiration, 
with the lungs in the deflated phase. The duration of 
this apnea averaged 26 seconds. For exposure periods 
of 1 minute the average reduction of lung output was 
62 per cent. If the vagus nerves were cut prior to ex- 
posure, no reflex inhibition of breathing was ob- 
tained. In the case of the monkey the L{Ct)^ data 
give no indication of breath holding during a 1-min- 
ute exposure (Table 1). The monkey is by far the 
most sensitive species tested with CG and the lethal 
concentration (0.6 to 1.0 mg/1) in this case appears 
to be below the level capable of inducing the reflex 


SECRET 


TOXICOLOGY 


19 


Table 2. Comparison of L(Ct)ioS of CG, AC, and CK. 


Species 

Exposure 

time 

(min) 

L(C05o AC 
L(C05o CG 

L(Ct)oo AC Density CG* 
L(Ctho CG ^ Density AC 

L{Ctho CK 
LiCtho CG 

L{Ctho CK _ Density CG 
L{Ct)so CG Density CK 

Mouse 

1 

0.26 

0.52 

1.3 

1.5 


30 

1.6 

3.2 

4.0 

4.6 

Rat 

1 

0.24 

0.48 

2.0 

2.3 


30 



6.4 

7.4 

Guinea pig 

1 

0.75 

1.50 

5.4 

6.3 

Monkey 

1 

1.7 

3.4 

4.4 

5.1 

Dog 

1 

0.10 

0.20 

0.45 

0.52 


3 

0.22 

0.44 

0.93 

1.1 


30 



1.4 

1.6 

Goat 

2 

0.34 

0.68 

0.55 

0.64 


* Calcvilated for comparison on a per bomb basis. 


action. In the dog little or no apnea was produced by 
exposures to 0.65 and 1.2 mg/1 of CG.® 

It was sho\Yn following World War I ^® that in 
tracheotomized dogs inhaled CG was 60 per cent ab- 
sorbed during 73^, 10-, 15-, and 30-minute expo- 
sures. Based on the CG absorbed, the LDioo was about 
0.74 mg/kg. This value, when compared with the 
LD-oo of 0.95 mg /kg for absorbed AC in the dog (see 
Chapter 2), would indicate that for this species CG 
is intrinsically more toxic than AC. On the other 
hand, the approximate 30-minute L(Ct) 5 oS of AC 
and CK for the dog, which involve close to the same 
volume breathed, indicate that AC is slightly more 
effective on an LD^o basis than is CG for this species. 
But it is striking to note in Table 2 that on the basis 
of the dosages to which dogs are exposed (not the ab- 
sorbed dosage given above) AC is ten times as toxic 
as CG in short exposure periods (1 minute). This 
result is a function of the manyfold increase in mi- 
nute volume induced by AC coupled with the depres- 
sion of respiration produced by CG. These figures 
illustrate the importance of respiratory volume in 
any attempt to estimate the toxicity of CG for man. 

With a possible exception in the case of AC in the 
dog, for longer exposure periods such as 30 minutes 
CG is more toxic than AC or CK. The L(C<) 5 o's of 
the cyanide agents increase as a result of the detoxi- 
fication rate and the differences in respiratory vol- 
ume decrease in significance as the time is lengthened. 

The variations in sensitivity to CG within a given 
species are evidenced by the data on mice in Table 1. 
Two strains of mice were exposed under the same 
conditions in the same laboratory and gave widely 
differing L{Ct\o^. It is not certain whether the sensi- 
tivity is purely a function of strain. The Jackson 
mice were tough, scrawny, and extremely active and 
the Carworth mice were relatively fat and glossy, 


averaging 2 to 4 g heavier than the Jackson strain. 
From several sources there is evidence that within a 
given strain animals that have been deprived of food 
or water for a period before exposure are more re- 
sistant to To cite one example. Car- 

worth mice placed on a restricted diet leading to a 
weight loss of about 15 per cent were gassed for 
10 minutes along with a group of control animals al- 
lowed to feed ad libitum. Mortality in the restricted 
group was only 4/30 compared with 13/29 in the 
controls.® An abrupt change in environmental tem- 
perature was found to be another factor which af- 
fected the resistance of mice to CG.® Abnormal post 
exposure temperatures led to increased sensitivity. 
Effects of these types, whether they be due to de- 
hydration, fasting, strain, or temperature, probably 
account for the apparent discrepancies among mouse 
Z/(C 05 o determinations from different laboratories 
(Table 1). 

The comparison of the L(C05o’s of CG, AC, and 
CK in Table 2 shows that for short exposures CG is 
only one-fifth as effective as AC against the dog and 
is more than three times as effective as AC against 
the monkey. There is no evidence which permits 
establishment of the relative L{Ct)^Q for man. For the 
calculation of munition expenditures the Allies have 
employed the value of 3,200 mg min/m^ for CG in 
comparison with 5,000 for AC and 11,000 for CK. 
Taking into consideration the relative liquid densi- 
ties of the three agents, the toxicity estimates which 
have been used on a per bomb basis are in the order 
of 1/3/4. It will be noted that the ratios of these 
values are similar to the ratios given for the monkey 
in Table 2. 

An estimate of the relative values of the toxicities 
of CG and the cyanide agents is only a part of the 
picture. The relative suitabilities of the three agents 


SECRET 


20 


PHOSGENE 


in the field would also be a function of additional im- 
portant considerations. CG kills only after a delay of 
a number of hours, whereas AC and CK were stand- 
ardized as “quick-acting” nonpersistent agents. CG 
also produces serious casualties in sublethal dosages 
and individuals may require hospitalization for sev- 
eral weeks prior to recovery. AC and CK in general 
produce no extended disability if the quantity in- 
haled is less than the lethal dosage. Injurious sub- 
lethal dosages of CG may be received prior to 
masking or after masking in the presence of high 
concentrations of CG if hurried adjustment of the 
facepiece leads to the presence of small leaks. 

For the production of casualties by attainment of 
effective dosages in less time than is required to mask, 
the toxicological data point to the working hypothe- 
sis that CG is the preferable agent if delayed effects 
are acceptable.^® This estimate takes into considera- 
tion both deaths and disablement of troops from 
sublethal dosages. If the tactical situation requires 
immediate deaths, the choice lies only with AC and 
CK. For harassment CG is considered the most satis- 
factory nonpersistent agent in view of its disabling 
action in sublethal amounts. 

Studies have been made of the effects of breathing 
low concentrations of CG for long periods to deter- 
mine the health hazards from trace concentrations 
which might be encountered in manufacturing oper- 
ations. British investigators exposed animals to a 
concentration of 0.0044 mg/1 (1/1,000,000) for 5 
hours on 5 successive days. Microscopic findings 
showed that all the animals were affected by CG to 
a degree likely to give rise in man to serious clinical 
symptoms. The experiments were repeated at a CG 
concentration of 0.0009 (1/5,000,000). Evidence of 
slight pulmonary edema and bronchitis was observed 
even at this low concentration.^^ It was concluded 
that at this concentration the limiting level of safety 
has approximately been reached. It will be noted 
that 0.0009 mg/1 is below the median detectable con- 
centration by odor measured with the osmoscope.^^ 
This does not necessarily mean that dangerous con- 
centrations of CG may be undetectable by odor. 
The osmoscope values are useful for laboratory com- 
parison of the detectability of different gases. It is 
known, however, that in free air, where an average 
low concentration is actually present in instantane- 
ous peaks and valleys of concentration, a person is 
aware of the presence of mustard gas, for example, 
at average concentrations much below the osmoscope 
value. 


3.3.2 Pathology 

The basic data on the pathology of phosgene poi- 
soning were reported following World War I.^^ The 
subject was reviewed in 1943 ^3 with reference to the 
observations made since that time, including studies 
by the Medical Division, Chemical Warfare Service, 
and the Committee on Medical Research [CMR] of 
the Office of Scientific Research and Development 
[OSRD]. The most recent CMR data on the pa- 
thology are summarized elsewhere. In man and 
experimental animals the factor initiating the patho- 
logical changes in the lungs is bronchiolar injury. 
Gassed patients die most frequently in the second 
half of the first day in pulmonary edema, with or 
without peripheral circulatory failure. Residual ef- 
fects of phosgene poisoning in human subjects have 
been summarized by the Medical Division. 

3.3.3 Physiological Mechanism and Therapy 

CG injures lung tissues by virtue of combination 
with cell constituents. With the simpler amino acids, 
for example, the reaction product is an amino acid 
ureide, O = C(NHCHRCOOH) 2 . Investigations by 
the Committee on Medical Research have shown that 
CG is capable of reacting under physiological condi- 
tions with -NH 2 , -SH, and -OH groups of amino 
acids, peptides, and proteins.^^^"-^^'^'*'' The reactivity 
of CG towards proteins produces in enzymes and 
hormones irreversible inhibitions of their enzymatic 
and hormonal activities.^^*^'^*' Experiments with CG 
containing radioactive carbon have established the 
fact that a significant percentage of the inhaled agent 
is bound locally in the lung tissue, paralleling the re- 
sults on the tissue fixation of radioactive mustard 
(see Chapters 22 and 23). 

The early theory that CG might exert its toxic 
action by virtue of the hydrochloric acid liberated 
intracellularly on hydrolysis has been shown to be 
un tenable. Part of the evidence is the parallelism 
between the toxic action of ketene (CH 2 = C = O) 
and CG. Ketene kills animals with the same clinical 
picture of lung edema and with the same histological 
injury to the lungs as is produced by CG. The 
L{Ct)f>Q^ of ketene for different species are of the same 
order of magnitude as those of CG.^® Ketene, how- 
ever, produces no mineral acid on hydrolysis. Also 
hexamethylenetetramine serves as a prophylactic 
agent against ketene as well as against CG, the pro- 
phylactic action resulting from competition for the 
toxic agents between the hexamethylenetetramine 


SECRET 


DIPHOSGENE 


21 


and the amino or other reactive g:roups of the cell 
constituents.*^^ 

The extensive studies on the treatment of CG casu- 
alties have been reviewed 1 ^- 23.24 g^^d summarized. 
Agents such as hexamethylenetetramine are effective 
if administered prior to exposure but have no prac- 
tical application to the soldier in the field. The 
knowledge on the general treatment of pulmonary 
edema has been extended through studies on the ap- 
plication of oxygen therapy under positive pressure 
in the case of CG casualties. In general no procedures 
have been found which have therapeutic value spe- 
cifically effective against phosgene poisoning as dis- 
tinguished from pulmonary edema of different 
etiology. 

3.4 EVALUATION OF CG AS A WAR GAS 

When delayed physiological effects are acceptable, 
CG has been considered the most economical stand- 
ard non persistent agent for the production of casual- 
ties by attainment of effective dosages in less time 
than is required to mask or for production of casual- 
ties among unprotected personnel.^® 

3.5 DIPHOSGENE 

Trichloromethyl chloroformate, diphosgene (DP), 
was used as a combat gas by the Germans in World 
War I. The fact that DP could be filled into ordinary 
HE shell by the simple expedient of cementing the 
joints was of importance to the Germans.'*^ With the 
development of special shell and bombs for plant 
filling with CG the interest in DP became less. For 
the task of production of lethal dosages in 30 seconds 
or 1 minute the more volatile CG was preferable. 
Interest in DP was temporarily renewed in World 
War II when it was shown that DP could be rapidly 
converted catalytically to CG in shell and a study 
was made of whether plant fillingwith DP followed by 
conversion to CG in the munition would be a useful 
procedure. The advantages of this method did not 
appear to offset the increased production costs for 
DP and the modifications of standard munitions re- 
quired in some instances. The more recent data on 
the chemistry and toxicology of DP are included in 
the following brief summary of work on this subject. 

DP boils at 127.5-128 C at atmospheric pressure 
and freezes at —57 C.'*® Its specific gravity is 1.645 
at 20 C,^ and its vapor density relative to that of air 
is 6.9. DP reacts with aniline in aqueous solutions or 
in benzene to give quantitative yields of carbanilide. 


This reaction may be used for detection and analy- 
sis."*® 

DP was first prepared by Hentschel in 1887 by 
the chlorination of methyl formate in direct sunlight. 
Methyl chloroformate was employed as a starting 
material by the Germans in World War I. Thorough 
studies by the French indicated that the 

photochlorination of methyl formate proceeds with 
increasing difficulty as the number of hydrogen 
atoms replaced increases, and that the last stage is 
slow unless adequate illumination rich in the shorter 
wavelengths is used. It is possible to conduct the 
later stages of the chlorination at higher tempera- 
tures, although the French workers recommended a 
temperature not exceeding 90 C, since decomposition 
of the product to CG becomes appreciable at higher 
temperatures. 

The direct chlorination of liquid methyl formate 
leads to considerable charring and may become vio- 
lent. To avoid undue loss of the volatile methyl 
formate, very efficient cooling of the by-product gas 
must be maintained. To minimize these difficulties, 
chlorination can be carried out in dilute solution, 
diphosgene itself being a convenient solvent. ^ Using 
a laboratory batch process employing this solvent 
and internal illumination from low-pressure dis- 
charge tubes, methyl formate can be converted into 
excellent quality DP in yields of 92 per cent on the 
ester and 90 per cent on the chlorine.^ In this process 
it is necessary to carry out the final stages of chlorin- 
ation at 80 C because of the low velocity of the last 
chlorination step. This temperature appears to be 
about the maximum which can be used without pro- 
hibitive losses of DP through conversion to CG.^ 

A continuous process based on the above method 
has been operated on a pilot plant scale. A total of 
about 1,000 lb of DP was produced in 86 per cent 
yield on the ester, 55 per cent on chlorine, by this 
pilot plant, which consisted essentially of two 5-1 re- 
actors in series, each reactor being illuminated by a 
well containing a 200-w projection lamp. Liquid 
methyl formate and gaseous chlorine were introduced 
into DP in the first reactor, which was operated at 
50-55 C and received 80 per cent of the chlorine in- 
put. The overflow from this reactor was led to the 
second reactor, which was maintained at 75-80 C 
and which received 20 per cent of the chlorine input. 
The product overflowed from the second reactor and 
was cooled and scrubbed with dry air to remove HCl 
and CI 2 . All stages of the reaction are exothermic, 
and the capacity of tlm unit appeared to be limited 


SECRET 


22 


PHOSGENE 


by the rate at which heat could be dissipated from 
the first reactor, in which most of the chlorination 
occurred. Rough estimates indicate that 121 kcal 
must be removed per mole of methyl formate used. 
A program to determine design factors for a large- 
scale plant was not completed.^ 

A continuous two-stage process has been developed 
by the Canadians for the photochlorination of 
methyl formate to DP. It is similar to the above 
process in that DP is used as a diluent but different 
from it in that chlorine concentrations approaching 
saturation are used, better pro^dsion for the dissipa- 
tion of heat during the initial stages is pro\*ided. and 
the charge is allowed to remain considerably longer 
in the second stage. In agreement with earlier work, 
the reaction was found to have a high temperature 
coeflBcient and to be promoted by light of wavelength 
shorter than 5300 A. The \’iolet mercury* line of com- 
mercial “blue neon" discharge tubes proved to be 
highly effective as a light source. The process gives 
DP in 85 per cent ^ield based on methyl formate, 
and has been operated on a pilot plant scale to wld 
2 lb per hour of good quahty DP in a >4eld of 87.5 
per cent on method formate and 68.4 per cent on 
chlorine.* 

Commercial chlorine contains some substance, 
possibly ox^’gen. which markedly inhibits the chlo- 
rination of methyl formate.--*-^ A’enting of the 
chlorine cylinders used removes this impurity, and 
satisfactoiN' chlorination results thereafter, although 
the loss of chlorine may be considerable.* 

Decomposition of DP to CG can be effected by 
heat. The reaction is accelerated by activated carbon 
and some metallic hahdes.^-^^ ^ Work carried out 
in this country’ in 1941 indicated that in addition to 
the known thermal and contact-catalyzed decompo- 
sition of DP to CG. this decomposition was remark- 
ably susceptible to catalysis by organic bases.*"* A 
number of liquid amines, e.g., p^Tidine, produce a 
\'iolent and almost instantaneous conversion. The 
.suggestion was made that bombs could be charged 
with DP and stored as such, the catah’tic conversion 
being made to proceed rapidly by the use of p\Tidine 
as cataly.st after the release of the bomb. A prelimi- 
naiN' model of a device by which this might be ac- 
complished was designed and constructed.* However, 
the production of a bomb incorp)oratmg such a de- 
vice presents several difficulties, and the advantages 
were not considered .sufficient to merit further re- 
search and development. Solid amines, .such as 
iNlichlers ketone, produce a slower decomposition, 


the rate of which can be in part controlled by con- 
trolling the proportion of catalyst, its rate of disso- 
lution, and the temperature. It was suggested that 
gas shell could be charged \s'ith DP, which is simpler 
than filling w*ith low-boiling CG, a pellet of catalyst 
containing Michler's ketone added, and the shell 
closed, after which ‘conversion to CG would take 
place. Laboratory' experiments indicated that this 
conversion would be substantially quantitative and 
complete within an hour. 

In attempting to work out the details incident to 
the use of solid catalysts for the conversion of DP 
to CG in shell, it was soon discovered that tempera- 
ture effects play a critical role in the course of the re- 
action. If the catalyst pellet disintegrates rapidly, 
the strongly exothermic dissociation of DP quickly 
warms the liquid to a certain critical temperature, 
after which the decomposition proceeds ven' rapidly 
and to completion. If, however, the pellet disinte- 
grates slowly, or the temperature and heat capacity 
of the bomb are such that this temperature is not 
reached, the conversion is never complete and is usu- 
ally not over 20 per cent. SmaU-scale experiments in 
glass vessels are thus valueless for the prediction of 
the beha™r of DP in actual munitions on the addi- 
tion of dissociation catah'sts. Experiments made 
with a metal bomb whose weight and void closely 
approximated those of a 105-mm shell indicate that 
a catalyst pellet composed of 2 parts Michler’s 
ketone, 5 parts p-dichlorobenzene, 1 part paraffin 
wax, 4 parts red lead when used in an amount equal 
to 1 to 1.5 parts per thou.sand of DP wnll produce 
satisfactory' cony'ersion. Lender these conditions, 
maximum temperatures of 42—43 C, starting with 
the bomb and contents at 25 C. are reached, and 
momentary' pressure .surges of 250-275 psi, dropping 
to 30-35 psi after 24 hours, are obsery'ed.^ The func- 
tion of the p-dichlorobenzene and the paraffin in the 
catalyst is to prey'ent too rapid disintegration of the 
pellet; that of the red lead is to increase the den.sity 
so that the pellet will not float on the DP. 

The phenomena which occur after the addition, of 
such a pellet to a sample of pure DP are striking. 
Michler’s ketone forms with CG a deep blue addition 
compound. On addition of the pellet a faint layer of 
blue appears on the surface of the DP, and the red 
pellet turns almost black. After sey'eral minutes the 
pellet begins to disintegrate rapidly', and the liquid 
rapidly becomes colored an intense blue. During this 
period there is a shght ey'olution of gas, which sud- 
denly becomes y'iolent and continues until the 


SECRET 


CARBONYL CHLOROFLUORIDE 


23 


liquid has almost completely boiled away. The start 
of the violent ebullition, which can be determined on 
duplicate samples \\nthin 20 seconds, begins when 
the sample reaches 34 C and under controlled con- 
ditions can be used as a criterion of purity for 
DP.4.7.36.38* 'pJjp presence of hydrogen chloride in 
the DP increases its “ebullition time” considerably. 

When liquid DP is decomposed in this wa^’ in an 
open vessel, insufl&cient heat is produced to over- 
come the latent heat of vaporization of the CG pro- 
duced, and, in spite of an initial rise in temperature, 
the temperature of the liquid eventually falls below 
the boiling point of CG. If pyridine in amounts equal 
to 10-11 per cent of the weight of DP is used to cata- 
h'ze the decomposition, calorimetric experiments in- 
dicate that the heat produced is approximately equiv- 
alent to that required to overcome the latent heat of 
the phosgene produced.**^ iSeveral rough experiments 
indicated that it may be jx)ssible to produce instan- 
taneous clouds without cooling the immediate at- 
mosphere by the simultaneous mixing and bursting 
of DP plus 10-1 1 per cent pyridine. **** In view of the 
important contribution of the local inversion pro- 
duced by the cooling effect, which aids in the attain- 
ment of high dosages \s*ith nonpersistent agents, it is 
doubtful whether the production of a gas cloud with 
no fall in temperature would have advantages at air 
temperatures above the boiling point of CG. 

In aqueous solution DP jdelds 2 moles of CG.^ 
Much of the work on the mechanism of action of 
CG (see Section 3.3.3) has for convenience been car- 
ried out by the addition of DP to aqueous solutions 
or suspensions of cell constituents. The pathology’ of 
DP poi.soning is the same as that of CG.'*' The data 
on the toxicity of DP indicate that the L(C05o’s do 
not differ markedh' from those for CG but the de- 
terminations are not adequate for a close differen- 
tiation. For the mouse a recent determination (140 
animals) gives a 10-minute L(C05o of 3,600 mg 
min /m* for DP^ to be compared wdth values of 1,800 
and of 3,800 for CG (Table 1). 

3.6 CARBONYL CHLOROFLUORIDE 

The fluorine analog of CG, carbonyl fluoride, is of 
a low order of toxicity compared with CG and has 
not been considered as a potential war gas. The com- 
pound in which only one of the chlorines is replaced 
by fluorine, however, has merited special study.® 

Carbonyl chlorofluoride has been prepared in 

* Additional compounds related to CG but of minor interest 

are included in Chapter 11. 


fields approximating 25 per cent by heating CG with 
a tenfold excess of anhydrous hydrogen fluoride at 
125-145 C in a pressure vessel. Small amounts of 
antimony pentafluoride promote the reaction and 
with this catah'st lower temperatures can be used. 
The products of the reaction are hydrogen chloride, 
carbonyl fluoride, and carbonyl chlorofluoride, the 
last of which can be separated by distillation.^ It has 
also been prepared in low \ield by passing CG over 
calcium fluoride at temperatures from 150 to 325 C 
and at pressures from 7 to 79 cm of mercuiw'. From 
the amount of uncondensed gas produced it appears 
that the ratio of carbonyl chlorofluoride to carbonyl 
fluoride produced is greater than 1 at temperatures 
below' 270 C. The maximum conversion (6 per cent) 
w as obtained at 260 C.** 

Carbonyl chlorofluoride is a ga< boiling at —42 C. 
Its melting point is — 138 C.* Its odor closely resem- 
bles that of phosgene, various obsen^ers being in dis- 
agreement as to w hether the two are distinguishable 
by odor.®’* It reacts readily with solid .sodium hy- 
droxide or with soda lime, show s no tendency to etch 
glas«,® and undergoes no loss in toxicity on storage 
in copper for 13 months at ordinaiw' temperatures,* 
although storage in a tank lined with polymerized 
shellac led to decomposition.® 

The protection against carbonyl chlorofluoride 
afforded hy whetlerite charcoal is of the same order 
as that against CG.® 

For most species the toxicity of carbonyl chloro- 
fluoride is veiy' close to that of CG. For the mouse 
the lO-minute L(C0»o (220 animals) is 1,200 mg 
min m* * compared wdth 1.800 for CG in determina- 
tions on the same strain of mice by the same labora- 
tor>'. For the rat, guinea pig, and dog approximate 
determinations give 10-minute values of <2,700, 
<2,7(X), and <6,000 * to be compared wdth CG 
values of 1,400 (30 minutes), l,3(X)-2,200 (30 min- 
utos), and 4,200 (20 minutes). CG is apparently 
much more toxic than carbonyl chlorofluoride for the 
rabbit, for which the L{Ct)io of CG is <1,(XX) (30 
minutes) and that of the fluorine compound is ai>- 
proximately 7,000. Carbonyl chlorofluoride ^delds a 
s\Tnptomatolog>' and pathology’ corresponding to 
that following phosgene poisoning.* 

Any advantage which carbonyl chlorofluoride 
might have over CG would rest upon its lower boil- 
ing point, which might make it more effective in the 
production of crash concentrations. However, at the 
present t^me the procedures for its preparation are 
not satisfactory' for large-scale work.* 


SECRET 


Chapter 4 

DISULFUR DECAFLUORIDE 

By Birdsey Renshaw and Marshall Gates 


4.1 INTRODUCTION 

D isulfur decafluoride (S2F10) is a dense, highly 
volatile liquid whose comparatively odorless 
and nonirritating vapor is a lung-injurant similar in 
mode of action to phosgene; for some species it is at 
least as toxic as phosgene. It thus presents attractive 
features as a potential nonpersistent agent, and its 
synthesis has been carefully investigated by Cana- 
dian researchers, by NDRC Division 10, and by the 
Chemical Warfare Service. The synthetic methods 
developed to date require the use of elemental flu- 
orine and give maximum yields of only about 30 per 
cent. The consequent difficulty and expense of its 
production in quantity at the present time have pre- 
cluded serious consideration of its adoption as a 
standard agent. 

The stability and other physical and chemical 
properties of disulfur decafluoride appear well suited 
to its effective dispersal from chemical munitions. 
The gas mask canister can be expected to protect 
against it approximately as well as against phosgene. 
Consequently, if its large-scale production were to 
become feasible in the future, its merits as a non- 
persistent agent would be determined in large part by 
its toxicological properties, in particular by its toxic- 
ity for man, and by whatever advantages would 
accrue to a nonpersistent agent which, at least in the 
pure state and at moderate concentrations, is odor- 
less and nonirritating. At present there are available 
no data upon which might be based an estimate of 
the incapacitating and lethal doses for man. If, as is 
the case for several of the smaller mammalian species, 
disulfur decafluoride should prove to be as toxic as 
or somewhat more toxic than phosgene, it would 
have some advantages over currently standardized 
nonpersistent agents. If, as appears to hold for the 
monkey, it should prove to be only one- tenth as 
toxic as phosgene, its large-scale use in warfare could 
hardly merit consideration. 


® Based on information available to Division 9 of the Na- 
tional Defense Research Committee [NDRC] as of August 1, 
l94o. 


4.2 SYNTHESIS AND PROPERTIES’^ 

4.2.1 Synthesis 

Disulfur decafluoride was discovered in 1934 by 
Denbigh and Whytlaw-Gray.^^ It occurs as a by- 
product formed in small quantities (I per cent) dur- 
ing the synthesis of sulfur hexafluoride from sulfur 
and elemental fluorine. In spite of extensive studies 
during World War II, its preparation in quantity re- 
mains difficult and expensive; 12.25,29 
been possible to prepare it except by the use of ele- 
mental fluorine ® or to increase the yield based on 
fluorine above 30 to 34 per cent in spite of a thorough 
investigation of the reaction conditions. ® 
The procedures wUich have given the best yields uti- 
lize the reaction of elemental fluorine, either pure or 
diluted with 5 to 30 parts of nitrogen, with solid 
roll sulfur, either pure or diluted with potassium or 
sodium fluoride. Adequate cooling of the reaction 
vessel is essential and either the fluorine or the sulfur 
must be diluted; oxygen and moisture must be ex- 
cluded. Failure has attended attempts to convert 
sulfur hexafluoride, the principal product of the re- 
action, to disulfur decafluoride by a variety of meth- 
ods which include its passage through an electric arc 
and its reaction with hydrogen sulfide or with molten 
potassium. 

4.2.2 Physical and Chemical Properties 

Disulfur decafluoride is a colorless, mobile liquid 
boiling at 30.1 C; it solidifies at low temperatures 
and melts at — 53 C.^ Its liquid density is 2.00 at 
20 C, its vapor density approximately nine times 
that of air. The vapor pressure, which has been 
precisely determined as a function of temperature, 
is 235 mm at 0 C and 675 mm at 25 It is 

virtually insoluble in water (<0.005 per cent by 

For a more complete review the reader is referred to the 
Summary Technical Report of NDRC Division 10. 

The production of elemental fluorine has been the subject 
of intensive investigation by several NDRC groups. It now 
appears possible to produce it in quantity at relatively low 
cost. The reader may consult the Summary Technical Re- 
port of NDRC Division 10 for a review of this work. 


24 


SECRET 


SYNTHESIS AND PROPERTIES 


25 


weight), in 0.9 per cent sodium chloride, and in O.IM 
phosphate buffer at pH 7.4, but soluble in various 
common organic solvents it is somew^hat soluble 
in olive oil, with which it reacts to a limited extent. ^ 

The thermodynamic properties of disulfur deca- 
fluoride have been evaluated using both thermo- 
chemical data and statistical considerations, and 
from these the gas-phase equilibria of a number of 
possible reactions of the sulfur fluorides have been 
calculated. 

Disulfur decafluoride does not react with such 
agents as strong alkalis or acids, phosphorus pent- 
oxide, or common solvents; fluorine has no action 
upon it at temperatures up to its decomposition 
point (160-210 C), but chlorine attacks it to yield a 
slightly volatile liquid. 

On prolonged contact with aqueous solutions, 
disulfur decafluoride appears to produce acid, but 
this conclusion must be regarded as tentative because 
the tests were made with a commerical preparation 
which may have contained small quantities of hy- 
drolyzable impurities.^^’^^ 

On activated carbon, disulfur decafluoride is cata- 
lytically decomposed to sulfur hexafluoride and sulfur 
tetrafluoride, the latter presumably decomposing 
further to sulfur difluoride and sulfur hexafluoride; 
nearly one-half of the weight of the original material 
appears as the hexafluoride.^ Thermal decompo- 
sition, which is slow at 200 C but rapid at 300 C, 
appears to involve similar reactions and gives sulfur 
hexafluoride as the principal product.^ 

The ability of disulfur decafluoride to act as an 
oxidizing agent is an important property which may 
be involved in its physiological mechanism of action 
(see the following section) and which has been uti- 
lized in the development of methods for its detection 
and analysis. 

4.2.3 Detection and Analysis 

The comparative inertness of disulfur decafluoride 
limits the number of methods available for detection 
and analysis. Its oxidizing ability and its decompo- 
sition on charcoal have been utilized. 

A number of easily oxidizable substances, includ- 
ing several oxidation-reduction indicators, have been 
examined as detectors for disulfur decafluoride. 

Of these p-phenylenediamine and 5fs(p-dimethyl- 
aminophenyl) methane appear to be the most suita- 
ble. A quantitative colorimetric procedure using the 
former has been developed for the analysis of cham- 
ber air in toxicity determinations.^® 


Disulfur decafluoride may be detected in air in 
concentrations as low as 10 ^tg/1 by passing the air 
through charcoal and then filtering a fluoride ion 
indicator (e.g., thorium or zirconium alizarin sul- 
fonate) through the charcoal. For use in detector 
tubes, however, charcoal decomposition followed by 
recognition of fluoride ion by standard methods is 
less satisfactory than the use of oxidation-reduction 
indicators. 

The reaction of disulfur decafluoride with either 
sodium or potassium iodide to produce iodine can be 
used for both qualitative and quantitative analy- 
ses. 7 - 24 , 30 a reaction is suitable for determina- 

tions of concentration in gassing chambers and for 
analyses of canister effluents. Acetone bubblers, pre- 
ceded by alkali scrubbers to remove hydrolyzable 
sulfur fluorides, are customarily employed. 

The detection and analysis of disulfur decafluoride 
are reviewed in more detail in Chapters 34 and 37. 

4.2.4 Stability 

Disulfur decafluoride reacts slightly with iron at 
55 C, but the reaction is sharply terminated, possibly 
by the formation of a protective coating. There is no 
reason to believe that the material cannot be stored 
satisfactorily in mild steel containers.^-^^ 

That disulfur decafluoride possesses sufficient sta- 
bility to be dispersed without decomposition from 
explosive munitions is suggested by the results of the 
one test for which data are available. A 75-mm 
shell was exploded in a large chamber; subsequent 
chemical analyses and toxicological bioassays of the 
chamber air demonstrated that at least 82 per cent 
of the dispersed agent was recoverable as such. 

4.2.5 Canister Penetration 

The protection afforded by the modern gas mask 
canister against disulfur decafluoride is reviewed in 
detail ^ and the conclusion reached that it is com- 
parable to that afforded against phosgene. As an ex- 
ample, no disulfur decafluoride appeared in the efflu- 
ent for more than 130 minutes when the United 
States MlOAl canister was tested in the Intermittent 
Flow Canister Testing Apparatus E2 against 5 to 
6 mg/1 of the agent. However, small amounts of 
sulfur hexafluoride, which is odorless and relatively 
innocuous,^’^^'^^’^®^ penetrate charcoals almost im- 
mediately, and subsequently odorous and irritating 
substances (sulfur dioxide, hydrogen fluoride, or 

^ See the Summary Technical Report of NDRC Division 10. 


SECRET 


26 


DISULFUR DECAFLUORIDE 


thionyl fluoride) appear in the effluent in concentra- 
tions which progressively increase to attain intol- 
erable and potentially dangerous levels before 
toxicologically significant amounts of disulfur deca- 
fluoride® are passed.^ Addition of soda lime 
removes these decomposition products and thereby 
materially increases the dosage against which char- 
coal affords useful protection. 

4.3 TOXICOLOGY 

Disulfur decafluoride is to be viewed as a non- 
persistent lung-injurant producing casualties qualita- 
tively similar in character and time course to those 
caused by the inhalation of phosgene. At the concen- 
trations which have been tested, it does not produce 
lacrimation or skin irritation. In marked con- 
trast with phosgene and cyanogen chloride, for 
which the median detectable concentrations are less 
than 0.01 mg/1, pure samples are odorless and non- 
irritating to the respirator}^ tract when breathed 
briefly at concentrations of at least 0.2 mg/l.“ 
Other observers have ascribed to presumably impure 
preparations an odor similar to that of sulfur di- 
oxide, and on several occasions the sniffing 
of a commercially prepared sample, which had a sul- 
furous odor, was followed by the development of 
mild nasal irritation of several hours’ duration.^’^®’^^ 
It remains to be determined whether impurities were 
responsible for the odor and irritation described in 
the latter observations, and whether or not the pure 
material is odorless at concentrations higher than 
those which have been tested. 

4.3.1 Toxicity for Animals 

Most of the available toxicity data for disulfur 
decafluoride are summarized in Table 1. Included for 
the sake of comparison are the most nearly compa- 
rable data for phosgene (see also Chapter 3). By and 
large, the data do not substantiate a currently prev- 
alent impression that disulfur decafluoride is dis- 
tinctly the more toxic. Although this impression is 
probably correct for the mouse, rat, and goat, partic- 
ularly at short exposure times, the opposite relation 

® Thus, an interesting situation, which might or might not 
have military significance, could conceivably arise during ex- 
posures to high dosages of disulfur decafluoride; Masked 
troops upon inhaling the irritating but not dangerous sub- 
stances in the canister effluent might suppose their protection 
inadequate; upon removing their masks, they would be ex- 
posed to the much less odorous and irritating but vastly more 
toxic disulfur decafluoride. 


holds for the guinea pig and monkey. The dis- 
crepancy is striking in the case of the monkey; the 
data, unfortunately limited in number, suggest that 
for this species disulfur decafluoride is only about 
one- tenth as toxic as phosgene. 

Information bearing upon the effect of exposure 
time on the L{Ct)^o of disulfur decafluoride and upon 
its rate of detoxification in the body is scanty. The 
data (Table 1) indicate that the L{Ct)^Q of disulfur 
decafluoride does not vary significantly with exposure 
time over the range 1 to 30 minutes. Thus, this rela- 
tively odorless compound does not exhibit the in- 
creased L(CQ 5 o’s at short (1-minute) exposures 
which characterize phosgene and which have been 
associated with an inhibition of respiration due to 
sensory irritation (see Chapter 3), and it does not 
appear to be detoxified at a rate comparable to that 
for hydrogen cyanide (see Chapter 2). On the other 
hand, the results of a limited number of experiments 
suggest that animals can tolerate two to four 'expo- 
sures at 24-hour intervals to vapor dosages each of 
which is of nearly lethal magnitude.^^ 

A striking feature of toxicity data for disulfur deca- 
fluoride is the narrow range of concentration be- 
tween that causing no deaths and that producing 
100 per cent mortality; with phosgene, on the other 
hand, the dose-mortality curve is spread widely on 
the dose axis.^^ As a result the curves for disulfur 
decafluoride and phosgene may cross, the latter com- 
pound killing more animals at relatively low dosages, 
the former, more at higher dosages. In spite of the 
steepness of the dose-mortality curve, however, 
disulfur decafluoride in sublethal doses does produce 
pulmonary pathological changes which in man might 
be of clinical and military significance.^^® 

4.3.2 Symptomatology 

Animals utilized for toxicity determinations have, 
in general, been exposed to dosages of less than three 
times the L{Ct)^Q and to concentrations of less than 
5 mg/1. Under these conditions no obvious changes 
in respiration or other indications of sensory irrita- 
tion are apparent and the animals appear 

normal upon return to their cages; “ practically all 
fatalities occur between 1 hour and 2 days after ex- 
posure, the majority occurring between 3 and 20 
hours.^^’^^’^^ There seems to be a fairly definite in- 
verse correlation between dosage and time for 
death. “’27 In a typical case culminating in death 
after 3 to 6 hours, the animal begins to appear quiet 
and depressed after 1 to 2 hours, its respiration be- 


SECRET 


TOXICOLOGY 


27 


Table 1. Toxicity of disulfur decafluoride. 


Included are the most nearly comparable data for phosgene. Unless otherwise noted, the L(C06o’s are based on nominal 
concentrations and 10- or 15-day observation periods. 


Species 

Exposure 

time 

(min) 

Disulfur decafluoride 

Phosgene 

Estimated 

L{Ct)iQ 
(mg min/m®) 

Number 

of 

animals 

Time of 
death 

Refer- 

ence 

Estimated 

UCtho 

(mg min/m^) 

Number 

of 

animals 

Time of 
death 

Refer- 

ence 

Mouse 

1 

2,200 

160 


16b 

3,450 

240 

4 hr-3 days* 

14 


10 

1,960 

160 


16b 

1,800 

220 

14 


1 

1,400-2,000 

40 


11 






10 

1,340 

150 

1-48 hr 

11 






30 

1,000-1,400 

40 


11 






10 

1,900 

160 

<24 hr 

22 

3,650t 

109 

83% in 2 days 

21 


10 

1,000 

30 

U-20 hr 

27 






30 

l,620t 

160 


32 

l,980t 

175 


32 

Rat 

1 

2,300 

8 


30b 

6,500 

24 

<40 hr 

14 


10 

2,000-3,000 

30 

1-16 hr 

11 






20 





1,800 ±t 

46 


18 

Guinea 

1 





2,800 

28 

3 hr-2 days 

14 

pig 

10 

6,000 ± 

20 

1 hr-9 days 

11 





10 

4,000-6,000 

15 

4 hr-2 days 

27 

l,900t 



27 

Rabbit 

1 





7,500 ± 

8 

3 hr-4 days 

14 


10 

6,000 ± 

10 

5-18 hr 

11 






10 

4,000-6,000 

6 

7-21 hr 

27 

13,000t 



27 

Cat 

1 





3,300 

7 

<1 day 

14 


10 

4,500 ± 

10 

50 min-12 hr 

11 






10 

<4,000 

4 

6-8 hr 

27 

3,500t 



27 

Dog 

1 

5,000 

16 


16b 

7,000 

9 

<1 day 

14 

10 

4,000-6,000 

10 

6-20 hr 

11 






20 





4,200 

20 

6-20 hr 

14 

Goat 

10 

4,000-6,000 

9 

6 hr- 15 days 

27 

8,500t 



27 

Monkey 

1 





600-1,000 

13 

3-15 hr 

14 

(Rhesus) 

10 

9,000 ± 

10 

4-5 ^ hr 

16b 

1,200 

10 


14, 36 


* A few died after 3 to 10 days. f Analytical concentration. J Two-day observation period. 


coming shallow and rapid; after an additional 1 to 
2 hours, respiration becomes labored; cyanosis then 
soon sets in, to be quickly followed by asphyxial 
convulsions and death accompanied by a flow of 
colorless foamy fluid from the nose and mouth. “ 

In an experiment in which mice were exposed to 
a high concentration (45 mg/1), symptoms and 
death occurred with striking rapidity. The animals 
immediately flattened out on their bellies and began 
gasping for breath. All died within 6 to 11 minutes 
after the beginning of the 10-minute exposure.”’^^^ 

4.3.3 Pathology 

Disulfur decafluoride acts primarily as a pul- 
monary irritant, producing an anoxic death due to 
massive, fulminating pulmonary edema and hy- 
peremia. It differs from phosgene and chlorine in 
that it does not injure the columnar epithelium of 


the bronchi and bronchioles, the pathological changes 
being confined to the alveoli and the pulmonary con- 
nective tissue, and being more prominent in the hilar 
than in the peripheral portions of the lung.^^ Some 
observers have also reported acute vesicular em- 
physema and, in a large proportion of animals, 
marked pleural effusion inasmuch as the pleura 
show no evidence of acute inflammation, it has been 
suggested that the pleural fluid arises from the lym- 
phatics draining the edematous lungs.^^ In some in- 
stances marked edema of the mediastinum, accom- 
panied by distention of the mediastinal lymphatics 
has been noted. 

In comparison with phosgene, disulfur decafluoride 
produces in dogs a more fulminating lung edema and 
hemoconcentration but less marked blood pressure 
or other circulatory changes. The hematocrit 
may rise slowly for some hours and then leap to high 


SECRET 


28 


DISULFUR DECAFLUORIDE 


values. Plasma protein concentration arises progres- 
sively. There is no initial bradycardia such as that 
which occurs with phosgene, and, in contrast to 
poisoning the latter agent, the pulse rate does not 
become greatly accelerated in the late stages. Arterial 
and venous pressures are little altered. Respiration 
is increased more gradually than by phosgene but 
eventually rapid and shallow breathing is established. 
Arterial and venous oxygen concentrations fall 
slowly at first, and then rapidly to values incom- 
patible with life. 

No extrapulmonary pathological changes other 
than congestion and fatty degenerative changes in 
the liver and kidney — effects presumably secondary 
to lung edema — have been reported as sequelae of 
inhalation of the vapor;^^’^^’^'^’^^ in particular, the 
eyes, nasopharynx, trachea, and lymphoid tissue 
appear normal. Observations on the corneal circula- 
tion of gassed dogs revealed hemoconcentration but 
not the other changes (cell clumping, vessel spasm, 
and local transudation of fluid) which have been ob- 
served in phosgene poisoning.^® Dogs with one bron- 
chus plugged during gassing and the other plugged 
subsequently to prevent edema fluid from pouring- 
in to the protected lung sometimes survived expo- 
sures to what would have been lethal dosages for 
normal dogs, and regularly lived longer than bilater- 
ally gassed animals; the protected lung remained 
grossly and microscopically normal.^® 

4.3.4 Physiological Mechanism 

The physiological mechanism of action of disulfur 
decafluoride has not been systematically investigated 
and definitive conclusions cannot be drawn at the 
present time. It is evident from the findings reviewed 
above that the significant pathological changes con- 
sequent upon inhalation of the vapor are confined to 
the pulmonary tissues. That other ti.ssues are sus- 
ceptible, however, and would be affected if sufficient 
quantities of the agent reached them, is indicated by 
the action on hemoglobin and by the lethal effects of 
intraperitoneal injections (see below). 

In evaluating the significance of the following iso- 
lated findings bearing on mechanism, and in planning 
future studies, the following facts set forth in the 
chemical section above may be recalled: (1) disulfur 
decafluoride acts as an oxidizing agent, and (2) its 
carbon-catalyzed decomposition in the presence of 
moisture involves the formation of sulfur hexafluoride 
and other substances among which may be thionyl 
fluoride, hydrogen fluoride, and sulfur dioxide. 


As in the case of water and salt solutions, addition 
with shaking of a plant- run sample of disulfur deca- 
fluoride to blood plasma resulted in the slow pro- 
duction of acid; the experiment has not been repeated 
with the purified compound. In the presence of 
the same plant-run sample, bromthymol blue in 
O.OIM phosphate buffer at pH 7.4 faded irreversibly 
in about 1 day; the rate of fading was accelerated in 
the presence of dissolved sodium chloride and in 
more alkaline solutions. It is rot known whether 
this reaction was an oxidation of the indicator or 
merely an acceleration of the tendency of brominated 
sulfonphthaleins in aqueous solution to form the 
corresponding carbinols. 

Upon shaking whole blood with the plant-run di- 
sulfur decafluoride, the hemoglobin slowly darkened 
with the evolution of gas bubbles. Addition of an 
acetone or ether solution of the agent produced these 
effects immediately. Solutions of oxyhemoglobin ob- 
tained by hemolyzing and filtering blood behaved as 
did whole blood. At pH 7.4 the absorption spec- 
trum of the altered pigment resembled that of met- 
hemoglobin in general features but not in all details; 
over the wavelength band 370 to 700 m/x it had 
no resemblance to the spectrum of oxyhemoglobin 
treated with sodium fluoride. 

Rapid local damage and death with hemoconcen- 
tration follow the intraperitoneal injection of di sulfur 
decafluoride as liquid or vapor. In one experi- 
ment with a rat injected with the gas, death occurred 
with extreme hemoconcentration after a latency of 
2 hours; at autopsy the lungs were clear but the 
peritoneal cavity contained 3 cc of fluid; injection of 
this fluid into a second rat had no detectable 
effects.^* 

A single analysis of the pleural fluid accumulating 
after lethal gassing with disulfur decafluoride re- 
vealed a fluorine content of 2 mg/100 ml.^^*^ 

Traces of sulfur hexafluoride were obtained from 
the reactions of disulfur decafluoride with olive oil 
and with pieces of excised rat lung; the reactions 
were sharply limited in extent. 

4.3.5 Prophylaxis and Therapy 

The results of a single exploratory study’ ^ indicate 
that prophylactic inhalation of magnesium carbonate 
dusts and intramuscular injection of magnesium 
sulfate solutions may have limited value in prolong- 
ing and saving the lives of mice gassed with disulfur 
decafluoride. Intraperitoneal injection of calcium 
chloride following exposure appeared to be harmful 


SECRET 


EVALUATION AS A WAR GAS 


29 


Table 2. Physical properties of disulfur decafluoride and of currently standardized nonpersistent agents. 

Property 

Disulfur 

decafluoride 

Phosgene 

Hydrogen 

cyanide 

Cyanogen 

chloride 

Liquid density (g/ml at 25 C) 

2.0 

1.36 

0.68 

1.2 

Vapor density (air = 1) 

8.1 

3.4 

0.93 

2.0 

Boiling point, C 

30.1 

8.3 

26 

12.6 

Melting point, C 

-53 

-104 

-13.4 

-7 

Latent heat of evaporation, cal/g 

25 

60 

210 

135 

Vapor pressure, mm Hg 
at 25 C 

675 

1,400 

740 

1,200 

at -20 C 

87 

230 

88 

180 

Volatility, mg/1 
at 25 C 

9,000 


1,060 


at -20 C 

1,400 

1,460 

145 

680 


and the inhalation of calcium carbonate dusts prior 
to exposure was without clear effect. Prophylactic 
injections of hexamethylenetetramine, a chemical 
specific for phosgene, were without effect, and 2,3- 
dimercaptopropanol (BAL), a similar specific for 
arsenic and cadmium, was detrimental. Prophylactic 
intramuscular injections of pitressin did not alter the 
course of the poisoning; exercise immediately subse- 
quent to exposure w^as not harmful. 

4.4 EVALUATION AS A WAR GAS 

Because of the difficulty and expense of manufac- 
ture on a large scale at the present time, it has not 
been practicable to make disulfur decafluoride for 
use in World War II. The available information does 
not permit a clear decision as to w'hether it would 
possess greater general utility than currently stand- 
ardized agents if its production and use in quantity 
were to become feasible. At the present time it should 
be evaluated in comparison wdth phosgene, the 
standard agent to which it is most similar in physical 
and toxicological properties. In terms of current con- 
cepts of chemical warfare, the tentative conclusion 
seems justified that its use on the battlefield would 
not demonstrate it to be markedly superior to phos- 
gene as a casualty-producing agent and might reveal 
it to be definitely inferior. 

The physical properties of disulfur decafluoride 
are well suited to its dispersion in high concentrations 
as a nonpersistent agent (Table 2). Moreover its high 
liquid density would permit significantly greater 
amounts to be carried in any given munition than is 
possible with phosgene, cyanogen chloride, or hydro- 


gen cyanide. So far as is known, its stability would 
suffice to permit its storage in currently available 
chemical munitions and its dispersal from them with- 
out destruction. Its insolubility in water and resist- 
ance to h 3 Mrolysis would give it an advantage over 
phosgene for use under those conditions of terrain 
and meteorology which permit clouds of “non- 
persistent” gases to exist for many minutes. 

The protection afforded by modern gas mask can- 
isters against disulfur decafluoride, like that afforded 
against phosgene, is so good that with reasonable 
munitions expenditures one could not hope to set up 
dosages sufficiently large to break the canister, ex- 
cept under very special circumstances. One would 
therefore expect that the bulk of the casualties to be 
realized from its use would be among individuals 
who, because of lack of time, unawareness of the 
presence of the poison, or other reasons, would be 
exposed unmasked or imperfectly masked. Conse- 
quently, attention focuses on toxicological properties. 

To whatever the extent that relative lack of odor 
and of irritating properties are desirable in a non- 
persistent agent, disulfur decafluoride (at least in the 
pure state) has an advantage over phosgene and 
cyanogen chloride. However, the critical toxicologi- 
cal data, namely the incapacitating and lethal dos- 
ages for man, are not available. If, as holds true for 
some animal species, it is as toxic or more toxic than 
phosgene, its use (assuming availability) in place of 
this agent would merit consideration. If, on the 
other hand, it is only one-tenth as toxic as phosgene 
(as appears to be the case for the Rhesus monkey), 
its utility as an offensive agent would hardly merit 
its production for use in warfare. 


SECRET 


Chapter 5 

MUSTARD GAS AND OTHER SULFUR MUSTARDS 

By Marshall Gates and Stanford, Moore 


5.1 INTRODUCTION 

A MAJOR PART of the activities of Division 9 of 
the National Defense Research Committee 
[NDRC] centered around the defensive and offen- 
sive problems presented by mustard gas and closely 
related vesicant agents. Chapters in Parts III, IV, 
and V deal in detail with the mechanism of action of 
agents in this class and means for protection and de- 
tection. The present chapter deals mainly with the 
methods for preparation of mustard gas and its 
analogs, a tabulation of the compounds which have 
been prepared, and the basic toxicological measure- 
ments on the more important members of the 
series. 

Mustard gas (H) was the principal battle gas of 
the last year of World War I. H was the agent which 
was manufactured and stocked in the largest ton- 
nage for possible use in World War II. The more re- 
cent investigations on the subject of H have greatly 
extended the knowledge of the mechanism of action 
of the agent, the information on its behavior in mu- 
nitions under field conditions, and the means for 
protection against the vesicant action of the vapor 
and liquid forms of the agent. 

Two relatively nonvolatile vesicant agents have 
been studied in detail for possible use in mixtures 
with H. They are l,2-6fs(iS-chloroethylthio)ethane 
(Q) and 6fs(j8-chloroethylthioethyl) ether (T). These 
two agents have a higher vesicancy in contact with 
bare skin and greater persistence on terrain than H, 
but because of their low vapor pressure they lack the 
ability to produce casualties by vapor action. 

HQ and HT mixtures have been prepared on a 
small scale. For special purposes the nitrogen mus- 
tards would have some uses (see Chapter 6). Among 
the hundreds of compounds that have been studied 
in the sulfur mustard series since H was first used in 
1917, no agent has been found to have a more advan- 
tageous combination of toxicological, chemical, and 
physical properties than H. 


“ Based on information available to NDRC Division 9 as of 
Jan. 1, 1946. 


5.2 PRODUCTION PROCESSES FOR H, 

HQ, AND HT 

5.2.1 General Methods 

The original laboratory methods of Guthrie 
and of V. Meyer for the preparation of H^ were 
both put to use on an industrial scale during World 
War I. 

The Meyer process, applied to large-scale produc- 
tion by the German Dye Trust, consisted essentially 
of the chlorination of thiodiglycol by hydrochloric 
acid. The thiodiglycol required was prepared from 
ethylene chlorohydrin b}^ the action of sodium sul- 
fide.278 

The English had begun erection of a plant for the 
manufacture of mustard gas from thiodiglycol and 
thionyl chloride in 1918, but apparently the plant 
did not come into production before the end of 
World War I. Other chlorinating agents, such as 
phosphorus trichloride and thionyl chloride, have 
been used, and other processes, notably the action 
of hydrogen sulfide on ethylene oxide, are now avail- 
able for the preparation of thiodiglycol. 

The Guthrie process involves the interaction of 
ethylene and sulfur chlorides and has been formu- 
lated as follows: 

2CH2=CH2 -h SCI 2 S(CH2CH2C1)2 (1) 

2CH2= CH 2 H- S 2 CI 2 S(CH2CH2C1)2 + S (2) 

although the course of the second reaction is more 
complex than required by this equation. Various 
modifications of this process provided all the mustard 
gas used by the Allies in World War I, the three 
principal processes being: 

1. The French process (Cattelain process). In this 
process a 10 per cent solution of sulfur dichloride in 
carbon tetrachloride was saturated with ethylene, 
and the dilute solution of mustard gas so obtained 
was stripped to a concentration of about 85 per cent. 

2. The 60 C process. Dry ethylene was led into 
sulfur monochloride maintained at 55-60 C. Under 
these conditions about one-half of the excess sulfur 

^ Both Despretz and Riche appear to have prepared 
6is(jS-chloroethyl) sulfide before Guthrie. 


30 


SECRET 


PRODUCTION PROCESSES FOR H, HQ, AND HT 


31 


remained in solution as polysulfides, whereas the 
other half separated on standing or on treatment 
with moist ammonia. 

3. The Levinstein process. In this process, also 
known as the “30 C process,’’ pure ethylene was led 
into a mixture of sulfur monochloride and crude 
mustard gas maintained between 30-34 C. Under 
these conditions the precipitation of sulfur was mini- 
mized and charging operations were facilitated. This 
process had been investigated by Pope and his co- 
w^orkers and was successfully used on a plant scale 
by the British firm of Levinstein, Ltd., and by the 
United States Chemical Warfare Service [CWS]. 

The thiodiglycol method for the preparation of 
pure H was not used by the United States or Great 
Britain during World War II, although successful 
laboratory procedures for carrying out the synthesis 
by both batch and continuous processes have been 
worked out.^’^^*^® Apparently the Germans, as in 
1917-18, relied principally on this method for their 
mustard stocks, although the thiodiglycol was ob- 
tained by the action of hydrogen sulfide, synthesized 
catalytically from hydrogen and sulfur vapor, on 
ethylene oxide, and the hydrogen chloride was ob- 
tained by burning hydrogen and chlorine. 

Although the thiodiglycol process has not been 
used by the Allies to produce H, a modification of it 
has been used to produce HT based upon the Oxford 
and Davies’ discovery that the incomplete chlo- 
rination of thiodiglycol produces T in addition to H. 
This reaction has been used on a plant scale to pro- 
duce HT, which is a mixture of these two materials 
wdth smaller amounts of high molecular weight sub- 
stances.^^^ The process is carried out essentially as 
follows: thiodiglycol, preheated to 60 C and mixed 
with concentrated hydrochloric acid, is treated for 
1 hour with hydrogen chloride in a tile-lined vessel. 
During the treatment the temperature rises to 110- 
115 C. Variation of the reaction conditions, espe- 
cially the temperature, allows some variation in the 
composition of the product. Normally, a mixture of 
60 per cent H and 40 per cent T (nominal) is ob- 
tained. The 40 per cent T contains homologs of T 
and related compounds, including a small amount of 
l,2-6zs(j3-chloroethylthio)ethane (Q) formed from im- 
purities present in crude thiodiglycol. This mixture 
melts at about 0 C, and has excellent stability. It is 
more vesicant than H against bare skin. Two plants 
each capable of producing 50 tons per week of 
HT 60/40 were erected in England. 

The process has also received study under a CWS 


contract at the Monsanto Chemical Company, and a 
continuous process consisting essentially of counter- 
current passage of thiodiglycol and hydrogen chloride 
through a packed column has been developed. Super- 
heated steam is used both as a source of heat and as 
a means of steam-distilling off the H formed so that 
subsequent reblending can be made to produce HT 
of any desired composition. A pilot plant for the 
process has been designed. 

Pure T can be prepared through T glycol ^ by the 
action of thionyl chloride or by the photochemical 
addition of 5fs(i8-mercaptoethyl) ether to vinyl chlo- 
ride,®^’^^^ as described later in this section. 

During the course of an investigation of the French 
process for the continuous conversion of thiodiglycol 
into H, the British in 1939 isolated Q, known since 
1921, in small amounts from the product. Its forma- 
tion was shown to be due to an impurity, /S-mercap- 
toethanol, in the thiodiglycol used. Under the 
conditions of the reaction, this condenses with thio- 
diglycol to give Q glycol which is then transformed 
into Q. 

HO— CH 2 CH 2 .SH 

+ HO— CH 2 CH 2 — S— CH 2 CH 2 — OH ^ 

HO— CH 2 CH 2 — S— CH 2 CH 2 — S— CH 2 CH 2 — OH 

The reaction has been investigated by the British 
using different proportions of jS-mercaptoethanol and 
thiodiglycol under a variety of conditions, and has 
led to the so-called HQ process, in which a mixture 
of thiodiglycol and /3-mercaptoethanol containing 
about 15 per cent of the latter is added to an excess of 
concentrated hydrochloric acid at 80 
The product contains 25-30 per cent Q, together 
with a small amount of 5fs(j8-(jS-chloroethylthio)- 
ethyl) sulfide, and melts at about 5 C. Larger 
amounts of the latter substance are produced if the 
content of /3-mercaptoethanol of the charge is higher 
than 15 per cent. The process has been worked out 
only on a laboratory scale, but is considered capable 
of being carried out in the HT plants. The product 
is somewhat more vesicant than HT against bare 
skin. 

The HQ process has also been investigated under 
a CWS contract by the Monsanto Chemical Com- 
pany, whose conclusions are in substantial agree- 
ment with those of the British, except that optimum 
results were obtained by gassing with hydrogen chlo- 
ride a 10 per cent /3-mercaptoethanol in thiodiglycol 
solution previously mixed with hydrochloric acid. 


SECRET 


32 


3IUSTARD GAS AND OTHER SULFUR MUSTARDS 


The process developed was considered suitable for 
scaling up in existing L plantsd^® 

Pure Q can be prepared by the photochemical ad- 
dition of 1,2-ethanedi thiol to vinyl chloride, as de- 
scribed in Section 5.2.7. 

5.2.2 Sulfur Dichloride Processes 

Ethylene and sulfur dichloride react according to 
the equation: 

SCb + 2 C 2 H 4 ^ S(C2H4C1)2 

and processes employing sulfur dichloride are not 
attended by the sulfur precipitation or the poly- 
sulfide formation characteristic of sulfur mono- 
chloride processes, which are now considered obsolete 
by the British. The reaction is much more rapid than 
that between ethylene and sulfur monochloride, and 
adequate cooling is required. 

Sulfur dichloride exists at ordinary temperatures 
as an equilibrium mixture with sulfur monochloride 
and chlorine, approximately in the proportion 
85/10/5. The equilibrium is mobile at ordinary tem- 
peratures and it is consequently not possible to ob- 
tain pure sulfur dichloride by simple fractionation 
at atmospheric pressures, although at low temper- 
atures the rate of attainment of equilibrium is slow 
enough for fractionation at reduced presvsures to be 
effective. The discovery by British investigators that 
the presence of phosphorus pentachloride markedly 
decreases the rate of attainment of equilibrium, how- 
ever, has allowed the preparation in quantity of pure 
sulfur dichloride (99.5 per cent) by fractionation of 
the equilibrium mixture at atmospheric pressure in 
glass apparatus. Metals in contact with the dichlo- 
ride promote dissociation to a variable degree. Brass, 
one of the least active, when used in still construc- 
tion, allows production of sulfur dichloride of 98- 
98.5 per cent purity. 

The type of sulfur dichloride used affords a basis 
for classification of the various British H processes. 
Thus : 

1. HS (obsolete). In this process a 1/6 mixture of 
crude (equilibrium mixture) sulfur dichloride and 
carbon tetrachloride were treated with ethylene at 
25 C. The process was continuous and the product 
was obtained by stripping off the carbon tetrachlo- 
ride under reduced pressure to a content of about 
15 per cent, this being sufficient to reduce the melting 
point of the mixture to less than 5 C. 

2. HM and HB. HS produced by a modification 
of the procedure just described is stripped under 70- 


100 mm to a carbon tetrachloride content below 
1 per cent and is then diluted with 7-10 per cent 
monochlorobenzene or benzene to form HM or HB. 
These have better pres.sure stability than HS, chiefly 
because of the thermal decomposition of unstable 
factors (principally trichloromustard) during strip- 
ping. 

3. HMD, HBD, and HCD. These processes utilize 
pure sulfur dichloride, prepared b}^ continuous two- 
stage distillation of sulfur dichloride stabilized by 
phosphorus pentachloride. In the plant, the first 
distillation stage is carried out in a cupronickel col- 
umn to separate chlorine and sulfur dichloride from 
sulfur monochloride, and the second stage, which 
separates sulfur dichloride from chlorine, is carried 
out in glass. The continuous HMD reaction takes 
place in nickel reactors with only enough solvent 
(monochlorobenzene) present to give the required 
freezing point to the product, which requires no 
stripping. The reaction has been run with benzene 
and carbon tetrachloride as solvents, giving HBD 
and HCD. 

A similar process for two-stage distillation of sta- 
bilized sulfur dichloride using brass columns has been 
developed, and sulfur dichloride produced in this 
way and containing 1-1.5 per cent sulfur monochlo- 
ride gives HMD/B and HBD/B when used in the 
H processes. Further identifying letters signify the 
type of reactor used (nickel or cast iron).^^^ Heating 
for short periods (3^-1 hour) at 165-180 C imparts 
greatly improved pressure stability to HMD and 
HBD.235 

Apparently the Germans had also built plants for 
the continuous production of sulfur dichloride 
mustard. 

5.2.3 Sulfur Monochloride Processes 

1. South African {DESA) process. In this proc- 
ess controlled precipitation of the excess sulfur is 
achieved by using ethylene saturated with alcohol 
vapor. The gas is passed into a batch of sulfur mono- 
chloride held at 35 C and is recirculated after wash- 
ing and drying by brine cooling. A batch of 1,200 lb 
of sulfur monochloride requires 12 hours for reaction. 
After removal of the precipitated sulfur in a settler 
the H layer is stripped of a low-boiling fraction and 
then distilled at approximately 35 mm from a mild 
steel pot and condensed in lead. The pressure stabil- 
ity of the product is good.^^^ 

2. The CWS Levinstein process. This process has 
been standard with the American Chemical Warfare 


SECRET 


PRODUCTION PROCESSES FOR H, HQ, AND HT 


33 


Service since World War I, and extensive studies on 
the stabilization, storage stability, purification, com- 
position, and behavior in the field of Levinstein 
mustard have been carried out in this country. 

Sulfur monochloride is added to a seed charge of 
H in mild steel reactors to give a concentration of 
about 25 per cent. Ethylene is then passed in and 
further monochloride is added to maintain its con- 
centration between 18 and 22 per cent. On comple- 
tion of the addition, ethylene is passed in until the 
sulfur monochloride content falls to less than 0.05 per 
cent. The excess sulfur is largely retained in solution 
in the form of poly.sulfides. Nine hours are required 
to complete a 6-ton batch. Brine cooling is necessary 
during the early part of the reaction to maintain the 
temperature at 35 C. 

5.2.4 The Composition of Levinstein H 

Most of the early work on Levinstein H or on sul- 
fur monochloride H, since many of the early experi- 
ments were carried out on “60 C mustard,” was 
concerned with accounting for the excess sulfur re- 
quired by the equation 

2C2H4 + S 2 CI 2 — > rClCH2H4)2S + s 

Among the theories proposed to explain the failure 
of this sulfur to precipitate completely were the 
following: 

1. The excess sulfur is present in the mustard in 
colloidal solution — “pseudo-solution.” 264,272 g^p. 
port of this, the fact that the sulfur in 60 C H could 
be largely precipitated by heating to 100 C without 
changing the freezing point of the H was brought 
forward. Likewise, the precipitation of sulfur from 
30 C H on dilution with alcohol appeared to support 
this hypothesis. 

2. The sulfur is present as the dispersed phase of 
a two-phase liquid-liquid dispersion. The difference 
in properties of various Levinstein samples was held 
to be due to differences in the degree of dispersion. 
The precipitation of sulfur by the addition of ether 
without change in freezing point was attributed to 
the removal of the dispersed phase. Attempts to pre- 
pare stable dispersions, however, failed. 

3. The sulfur is present in the form of a loose com- 
pound with mu.stard itself.^®® As evidence for this 
point of view the insolubility of sulfur in H, together 
with the fact that sulfur dissolved in sulfur mono- 
chloride H by heating precipitates quantitatively on 
cooling, was presented. The sulfur cannot be com- 
bined with 5fs(/3-chloroethyl) sulfide itself, how- 


ever, unless the complex is dissociable at room 
temperature.^’^ 

Other early evidence for compound formation 
(not necessarily with H itself) was the production of 
sulfuric acid by oxidation of industrial H and 
of sulfuric acid and a chlorine-containing alkane 
sulfonic acid by oxidation of a distillation residue of 
the approximate composition (C1CH2CH2)2S5 from 
60 C A solid substance of the composition 

(0101120112)283 which could be oxidized to sulfuric 
acid and 2-chloroethanesulfonic acid was isolated by 
fractional distillation of 60 0 H and it was shown 
that its formation was favored by lower temperature 
reaction of ethylene and sulfur monochloride. 

4. The sulfur is present partly in combination, 
partly as a colloidal dispersion or solution. This 
hypothesis was based upon the fact that only a part 
of the excess sulfur can be precipitated by heating, 
freezing, or treatment with moist ammonia. 

In a series of distillation studies on Levinstein 
mustard of current manufacture carried out at Edge- 
wood Arsenal,^ the distillate obtained by the CWS 
specification assay for Levinstein H was subjected to 
fractional distillation and found to consist of pure 
6fs(j8-chloroethyl) sulfide (78 per cent) and a residue 
(20 per cent). Fractionation of the residue gave 
about 35 per cent of 5fs(j8-chloroethyl) sulfide, 28 per 
cent of 5fs(j8-chloroethyl) disulfide (HS2), and 20 per 
cent of residue, with about 15 per cent loss during 
the distillation. 

In order to minimize changes in composition oc- 
curring during distillation by ordinary methods, 
molecular distillation was resorted to. A preliminary 
distillation gave three fractions, the first of which 
was subsequently fractionated into three relate vel}^ 
volatile components, possibly chlorinated hydro- 
carbons, which contained no sulfur. The next two 
consisted essentially of 5fs(j8-chloroethyl) sulfide. 
The residue was rich in sulfur, containing 4.5 molec- 
ular proportions of sulfur to every 1 of chlorine. 

Repeated passage of crude Levinstein H through 
the molecular still at successively higher tempera- 
tures gave 6fs()S-chloroethyl) sulfide fractions progres- 
sively richer in sulfur. This increase was attributed 
to the presence of increasing amounts of HS2 in 
the distillate. The unstable residue from these dis- 
tillations could be separated into two components, 
an acetone-insoluble fraction having a composition 
corresponding approximately to (ClCH2CH2)2Si2, 
and an acetone-soluble fraction of composition cor- 
responding to (0101120112)284.5. The acetone-insolu- 


SEORET 


34 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


ble residue deposited sulfur when allowed to stand. 
Treatment with gaseous ammonia caused rapid pre- 
cipitation of sulfur, and the material remaining was 
found to have a composition corresponding closel}^ 
to (C1CH2CH2)2S5. 

Only slightly different results were obtained in 
similar distillation studies on Levinstein of 1937 
manufacture and on Levinstein of 1918 manufacture. 

From these results and those of other investigators 
it was postulated that the chief impurities in Levin- 
stein mustard were polysulfides of variable compo- 
sition. The transient existence of a poly sulfide of any 
definite composition was attributed to the probable 
ability of the — CH 2 SSCH 2 — linkage easily to gain or 
lose sulfur atoms. It did not appear possible to distill 
Levinstein H without altering its composition. 

A review of the evidence available at the time of 
this work indicated that Levinstein mustard was 
composed of : 

1. Gases, noncondensable at — 78C; probably 
ethylene. 

2. Chlorinated hydrocarbons; 1 per cent or less. 

3. jS-Chloroethyl jS-chlorovinyl sulfide as such or 
as trichlorodiethyl sulfide. 

4. 6zs(i3-Chloroethyl) sulfide; 60 to 70 per cent. 

5. 6fs(i3-Chloroethyl) disulfide; free and as poly- 
sulfides. 

6. Diethylene disulfide, partly free as monomer 
(dithiane) and polymer, and partly potential. 

7. Sulfur, free and as polysulfide. 

The results of some experiments on methanol ex- 
traction of Levinstein H also led to the conclusion 
that polysulfides are present.^^® Cold methanol ex- 
traction of a sample of American Levinstein H left 
an in.soluble residue of low vesicancy with the ap- 
proximate composition (C1CH2CH2)2S9. The soluble 
portion, after stripping of solvent and removal of 
most of the H by freezing, was again fractionated by 
methanol extraction, yielding an insoluble fraction 
of the approximate composition (C 1 CH 2 CH 2 ) 2 S 8 and 
a soluble fraction whose composition approached 
(C 1 CH 2 CH 2 ) 2 S 3 but which contained about 10 per 
cent H. In view of the now known lability of the 
higher jS-chloroethyl polysulfides, however, it may 
be unsafe to assume that material which has been 
stripped of methanol by distillation is unaltered. 

In 1943 a theory of the formation and composition 
of Levinstein H which explained many of the avail- 
able data was proposed by workers in the CWS. The 
salient points of this theory were the following: 

1. Sulfur monochloride was supposed to be an 


equilibrium mixture of at least the following com- 
ponents: sulfur in solution, sulfur dichloride, and 
two isomeric forms of sulfur monochloride, ClSSCl 
and CI 2 S S. 

2. Ethylene may react with all of these except 
sulfur. 

a. 2CH2-=CH2 -f- SCI2 — ^ 

CICH 2 CH 2 SCH 2 CH 2 CI 

b. 2CH2=CH2 -h CI 2 S S 

(C1CH2CH2)2S ^ s 

c. 2CH2=CH2 + ClSSCl 

CICH 2 CH 2 SSCH 2 CH 2 CI 

Since the compound (C1CH2CH2)2S — >■ S had not 
been isolated, it was postulated that it could have 
only a transient existence, decomposing into bis(^- 
chloroethyl) sulfide and sulfur. This “nascent sulfur” 
could then be taken up by the disulfide, CICH 2 CH 2 - 
SSCH 2 CH 2 CI, to form higher polysulfides. The num- 
ber of sulfur atoms in the poly sulfide would depend 
upon the proportions in which the two forms of the 
disulfide were present. For example, if the ratio were 
three to one, the resulting mixture would contain 
62 per cent by weight of 6zs(|8-chloroethyl) sulfide, 
and the polysulfide would be a pentasulfide. 

3(C1CH2CH2)2S ^ S + (C1CH2CH2)2S2 

3(C1CH2CH2)2S -f- (C1CH2CH2)2S5 

It was suggested that the ratio of CI 2 S — > S to 
ClSSCl might be changed by altering conditions so 
as to increase the amount of CI 2 S — S, which in 
turn would increase the amount of ?)fs(i3-chloroethyl) 
sulfide and sulfur formed. This would account for 
the higher yield of ?>fs(/3-chloroethyl) sulfide and 
for the precipitation of sulfur actually observed when 
the reaction is run at 60 C. 

Available analytical data on the sulfur-chlorine 
ratio in Levinstein mustard and on the relation be- 
tween freezing point and 6fs(jS-chloroethyl) sulfide 
content of Levinstein mustard were used to extend 
and support the hypothesis. It was postulated that 
the principal impurities in Levinstein had the 
structures 

CICH 2 CH 2 S— SCH 2 CH 2 CI, 

\ I 

S S 

s s 

t t 

C1CH2CH2S— SCH2CH2C1, 

I I 

s s 


SECRET 


PRODUCTION PROCESSES FOR H, HQ, AND HT 


35 


S S 

t I 

CICH2CH2S— SCH2CH2CI, 

I I 

s s 

I 

s 

^ etc. 

Excess sulfur could be stripped from impurities of 
this type without altering the mole fraction of im- 
purity and consequently the melting point should 
remain constant, as is actually observed. The his{0- 
chloroethyl) sulfide content of Levinstein H as de- 
termined by distillation and as calculated from its 
freezing point was shown to be very nearly the same 
on the assumption that the molecular weight of the 
impurity is 319, corresponding to 6zs(i3-chloroethyl) 
hexasulfide (HSe). If the equation 

2CH2=CH2 + SsCb-^ CICH2CH2SCH2CH2CI + S 

actually represents the Levinstein reaction, then it 
would appear that one atom of sulfur per molecule 
of H or about 16.8 per cent of the total product 
should be precipitated. Actually it is possible to in- 
duce only about half of this amount of sulfur to pre- 
cipitate from Levinstein mustard. Analyses of fresh 
Levinstein H show that it contains approximately 
37 per cent chlorine and 33 per cent sulfur, giving a 
sulfur-chlorine ratio of 1/1. It was postulated by the 
CWS workers that the 30 per cent impurity in 
Levinstein mustard was HSe, leading to a chlorine 
and sulfur content in the mixture of 37.9 per cent 
and 32.2 per cent, respectively. During aging or 
stripping HSe was assumed to lose sulfur until the 
more stable level HS4 was reached. 

S S 

t t 

CICH2CH2S— SCH2CH2CI ^ 

j I 

s s 

s s 

t t 

CICH2CH2S— SCH2CH2CI + 2 S 

This would represent a loss of sulfur amounting to 
6 per cent of the total weight of the product. It would 
have no effect on the mole fraction or on the freezing 
point but would raise the weight-fraction of his{^- 
chloroethyl) sulfide to about 0.75, with about 25 per 
cent of polysulfides still present. This mixture would 


contain 27.7 per cent sulfur and 40.4 per cent chlo- 
rine, which is in close agreement with the observed 
values for aged or stripped Levinstein mustard. 

This hypothesis, which has become known as the 
Reid-Macy hypothesis, as to the formation of and 
the composition of Levinstein mustard, was a sig- 
nificant forward step, but it was based on scanty 
experimental evidence and although substantially 
correct as an overall view, required considerable 
modification in the light of later experimental data.^^'^ 

The NDRC Division 9 group which undertook a 
study of Levinstein mustard in May 1943 intro- 
duced a valuable technique for the quantitative re- 
moval of 6fs(|(3-chloroethyl) sulfide from Levinstein H 
without altering the composition of the polysulfide 
fraction. This removal was achieved merely by ex- 
haustive hydrolysis, and its success depends'*upon 
the fact that the poly sulfides in Levinstein are stable 
toward water at room temperature, whereas 
chloroethyl) sulfide is readily hydrolyzed. The prog- 
ress of the hydrolysis is followed by titration of the 
hydrogen or chloride ion produced. When the rate 
of hydrolysis becomes negligibly small, the non- 
hydrolyzed residue amounts to about 30 per cent by 
weight of the original product. The composition of 
the dark, oily residues from different samples of 
Levinstein mustard is not the same but varies be- 
tween values corresponding to (C1CH2CH2)2S6 (HSe) 
and (C1CH2CH2)2S9 (HS9). 

These residues deposit sulfur slowly. When treated 
with Cellosolve, in which the polysulfides are fairly 
soluble but in which sulfur has very limited solubility, 
sulfur is observed to separate in the form of fine 
crystals, and a small amount of dark gum remains 
insoluble. This gum has the composition of a high 
molecular weight polysulfide such as (C 1 CH 2 CH 2 ) 2 Si 2 . 
It invariably deposits sulfur within a few days and 
takes on the appearance of crystalline sulfur. 

The soluble polysulfides can be recovered by wash- 
ing the Cellosolve solution with water until the Cello- 
solve is completely removed, drying the resulting oil 
in ether solution, and removing the ether. A clear 
amber oil, containing slightly less sulfur and slightly 
more chlorine than a compound having the compo- 
sition of 5is(i3-chloroethyl) pentasulfide, results. 

A more complete characterization of these poly- 
sulfides was made possible by their synthesis. Oils 
having the characteristics of higher polysulfides were 
prepared by heating the known HS3, with excess sul- 
fur under moderate conditions, by allowing it to 
stand in the presence of sulfur monochloride, or by 


SECRET 


36 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


heating it with methyl tetra- or pentasulfides. When 
these oils are stripped of their excess sulfur by the 
Cellosolve treatment or by moist ammonia, they re- 
semble the Cellosolve-stripped Levinstein residues of 
composition corresponding to HS5 in appearance, 
odor, refractive index, density, polarographic be- 
havior, and analysis. HS5 was also prepared by heat- 
ing HS2 with excess sulfur under more stringent 
conditions, although sulfur monochloride and methyl 
polysulfides had no sulfurizing action on this disul- 
fide. All of the synthetic polysulfides, if allowed to 
stand without being stripped with Cellosolve, de- 
posit sulfur gradually until the composition of the 
residual oil approaches that of the pentasulfide. The 
solubility of sulfur in HS5 proved to be about 7 per 
cent or 0.6 gram-atom so it is to be expected that 
sulfur would no longer be precipitated when the sul- 
fur content of the polysulfide had decreased to 5.6 
atoms, unless some potysulfide solvent which does 
not dissolve sulfur appreciably, e.g., Cellosolve, 
were added. 

The pentasulfide exhibits relatively high stability 
compared with higher polysulfides and was obtained 
in a state of high purity after methods had been 
worked out to remove various impurities always 
present in the nonhydrolyzable Levinstein residues. 
Attempts to distill HS5 or HS 5-mustard mixtures by 
ordinary vacuum distillation result in degradation of 
HS5 to HSa and HS2, both of which are readily dis- 
tillable. 

When HSo is subjected to steam-distillation, HS3 
is obtained in the distillate, and the nondistillable 
residue consists of poly sulfides higher than HS5. 
Autosulfurization of HSs appears to take place under 
these conditions, the removal of the volatile HS3 
forcing the reaction to proceed. Higher polysulfides 
prepared in this way are similar to the polysulfides 
isolated from fresh Levinstein mustard in that they 
slowly deposit sulfur over a period of weeks. This 
deposition of sulfur can be accelerated by the usual 
stripping methods to reproduce HS5. By steam-dis- 
tilling the impure polysulfide from Levinstein mus- 
tard for a short time to remove volatile impurities 
such as the disulfide and subsequently stripping the 
higher polysulfide residues with Cellosolve, pure 
HS5 can be obtained as a light amber, slightly vis- 
cous liquid with a much less pronounced odor than 
that of the unpurified material. The molecular 
formula, C4H8C12S5, has been verified by ultimate 
analysis. 

Although it is stable to moist ammonia in the ab- 


sence of a solvent, HS5 is stripped to HS3 by moist 
ammonia in the presence of a solvent such as ether 
or Cellosolve. Metallic mercury also strips sulfur 
from HS5, producing HS3 and HS2, although the 
rate at which the stripping proceeds is much less in 
going from HS3 to HS2 than in converting HS5 to 
HS3.^^ 

The stability of HS5 and HS3 and the degradation 
of HS5 to yield HS3 indicate that these compounds 
may be structurally related. HS2 is known to be a 
linear disulfide. One sulfur atom may be added with 
difficulty to HS2 but following this two additional 
atoms enter with comparative ease to give HS5. 
Degradation of this HS5 gives HS3. These phenomena 
can be accounted for most easily by assuming that a 
sulfur atom enters the HS2 molecule to produce a 
linear trisulfide of the structure CICH2CH2SSSCH2- 
CH2CI and that this molecule is then sulfurized to 
produce HS5 of the structure 

S 

t 

CICH2CH2SSSCH2CH2C1 

I 

s 

The higher polysulfides could be accounted for b}^ 
structures of the type 

S 

t 

s 

t 

C1CH2CH2SSSCH2CH2C1 

I 

s 

I 

s 

I 

etc. 

which would be in accord with the natural chain- 
forming tendency of sulfur atoms, and the limited 
stability of the higher poly sulfides. 

During a study of the composition of British 
Levinstein H, British investigators arrived at similar 
conclusions.^®^ When treated with cold acetone their 
sample, prepared at Sutton Oak, produced a milky 
suspension which gradually deposited crystalline 
sulfur. Only a small amount of sulfur was produced, 
apparently that in solution in the Levinstein mus- 
tard. Attempts to distill the higher boiling fractions 
of Levinstein failed because of the decomposition of 
a “labile polysulfide” which could be removed by 


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PRODUCTION PROCESSES FOR H, HQ, AND HT 


37 


preliminary refluxing of the higher boiling fractions 
with acetone. After this period of refluxing, the pre- 
cipitated sulfur was removed by filtration. The re- 
sulting material was found to be distillable under 
reduced pressure without decomposition to give 
HS2 and HS3, which were compared with synthetic 
samples. 

Examination of the labile polysulfide obtained as 
a residue from the preliminaiy low- temperature dis- 
tillation of Levinstein mustard revealed it to be a 
yellow, viscous oil, nearly insoluble in alcohol, pe- 
troleum ether, and acetone, but soluble in benzene, 
chloroform, and carbon disulfide. Similar material 
could be obtained as a residue by extracting Levin- 
stein mustard with methanol. The poly sulfide could 
be broken down partially to “2,2'-dichlorodiethyl 
trisulfide and sulfur ... by heating at about 100 C 
for a few hours. ...” This change could also be 
brought about slowly but completely by heating the 
labile poly sulfide under reflux in the presence of 
acetone, since one of the products of this breakdown 
is soluble in acetone and the other, sulfur, is not. 

Synthesis of the labile pol 3 ^sulfide was accom- 
plished by heating the tri sulfide with 3 gram-atoms 
of sulfur at HOC for several hours. After extraction 
of the product with methanol to remove unchanged 
trisulfide and separation by filtration from a small 
amount of unreacted sulfur, an oil resembling the 
original labile polysulfide remained. 

The trisulfide could be obtained by distillation of 
the methyl alcohol extracts of Levinstein mustard 
without the formation of much sulfur, indicating that 
some tri sulfide exists uncombined in the original 
mixture. 

The British investigators .suggested that the labile 
polysulfide probably contains compounds of the type 

CICH2CH2S S ^ S etc. 

I 

s^s 

I 

CICH2CH2S ^ s 

or perhaps, since mono- and disulfides do not form 
polysulfides when treated in the same manner, struc- 
tures with the additional sulfur atoms branching 
from the central S of HS 3 . 

HS 4 also appears to be a true level of stability, 
since HS 5 from different sources is stripped to this 
level on refluxing in acetone, and HS 3 on heating with 
sulfur in boiling acetone for several days undergoes 


sulfurization to a product who.se composition ap- 
proaches that of HS 4 .^^ 

A number of less direct lines of evidence point to 
higher polysulfides as the principal impurities in 
Levinstein H. 

Thus, in a .series of studies on fractional melting of 
Levinstein H samples, the densities and refractive 
indices of a number of fractions as functions of H 
content were recorded.-^ If the densities and refrac- 
tive indices of various Levinstein H fractions are 
plotted against their H contents, straight lines are 
obtained, which can be extrapolated to give the cor- 
responding values for the impurity treated as a single 
component. From the equations of these two lines it 
is possible to eliminate the H content, giving an ex- 
pression relating den.sity and refractive index. Ex- 
perimentally determined values for the refractive 
indices and densities of synthetic samples of HS 2 , 
HS3, and HS5 all fell on or very clo.se to this curve, 
but not so far out as the extrapolated values for the 
impurity, which were also on the curve. The indica- 
tions were that the impurity was a 6f5(/3-chloroethyl) 
polysulfide containing six or seven sulfur atoms. 

Two independent investigations upon the compo- 
sition of solvent extracts and steam distillates of 
Levinstein H using cryoscopic methods have been 
reported. In each, measurements of melting 
point and of average molecular weight, determined 
cryoscopically, of the samples have allowed calcu- 
lation of the mole fraction of the impurity and thus 
its average molecular weight. In one investigation 
the average molecular weights of the impurities in 
several extracts were 311, 291, and 250, correspond- 
ing roughly to HSe, IIS5, and HS4. In the other,*® 
the impurities in crude Levinstein were found to have 
an average molecular weight corresponding approxi- 
mately to HS7, whereas the average molecular 
weight of the impurities in Levinstein stripped with 
moist ammonia or completely extracted with pentane 
corresponded approximately to HS5. The results with 
steam-distilled material are divergent, indicating in 
one ca.se that low molecular weight impurities are 
present in sufficient quantities to bring the average 
molecular weight of the mixture below that of pure 
H, whereas in the other case *® significant amounts 
of HS 2 are indicated. 

Molecular distillations carried out on three samples 
of Levinstein H at temperatures not exceeding 30 C 
also indicate that the residues remaining after such 
distillations, during which the sample is not likely 
to have altered, are composed of polysulfides of com- 


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38 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


Table 1.^® Mixtures of H and HSj:. 


Mixtures of H and HSj- which have the composition of the mixture Mixtures of H and HS 5 

one molecule of H plus one atom of sulfur produced by stripping 

Weight 
(per cent) 



Mixture* 

Mole 

ratio 

Mole 
(per cent) 

Weight 
(per cent) 

Calcd. 
fpt in C 

strippable 

sulfur 

Mixture* 

Weight 
(per cent) 

Chlorine 
(per cent) 

Sulfur 
(per cent) 

1 . 

H 

3 

75 

62.5 

5.6 

0 

H 

62.5 

37.2 

33.5 


HS 5 

1 

25 

37.5 



HS 5 

37.5 



2. 

H 

4 

80 

66.8 

7.2 

3.4 

H 

69.0 

38.5 

31.2 


HSs 

1 

20 

33.2 



HS 5 

31.0 



3. 

H 

5 

83.3 

69.5 

8.5 

5.5 

H 

73.6 

39.4 

29.6 


HS; 

1 

16.7 

30.5 



HSs 

26.4 



4. 

H 

6 

85.7 

71.5 

9.1 

7.2 

H 

76.9 

40.0 

28.3 


HSs 

1 

14.3 

28.5 



HS 5 

23.1 



5. 

H 

7 

87.5 

72.9 

9.7 

8.4 

H 

79.6 

40.6 

27.4 


HSa 

1 

12.5 

27.1 



HS 5 

20.4 



6 . 

H 

8 

88.9 

74.1 

10.4 

9.3 

H 

81.7 

41.1 

26.7 


HSio 

1 

11.1 

25.9 



HS 5 

18.3 



* .\11 these mixtures of H + HS* contain 33.5 per cent S and 37.1 per cent Cl. 


t These freezing points were interpolated from the “Mean Curve.”i® 

positions and molecular weights corresponding to 
HSft, HSe, and HS?. Indices of refraction of the resi- 
dues from two of these fractions appear to be in 
agreement with this assumption.^^ 

In summary there appears to be much trustworthy 
evidence indicating that Levinstein mustard is chiefly 
a solution of 6fs(i3-chloroethyl) sulfide and polysul- 
fides of varying composition and stability and of the 
general formula, (ClCIl 2 CH 2 ) 2 Sa;. Part of the excess 
sulfur is used in forming the stable linear trisulfide 
skeleton and this sulfur cannot be removed by ordi- 
nary methods of stripping. The pentasulfide repre- 
sents another stable level. Aged Levinstein mustard 
or Levinstein mustard stripped by the usual methods 
involving moist ammonia, consists essentially of a 
mixture of 6fs(i8-chloroethyl) sulfide and HS5. Con- 
sideration of the amount of sulfur formed by the 
stripping process, the amount of pentasulfide which 
can be isolated from Levinstein, and the freezing 
point of fresh Levinstein leads to the conclusion that 
the poly sulfide in freshl}^ prepared Levinstein mus- 
tard may have an average composition varying from 
that of the hexasulfide to that of the decasulfide. 
Usually the poly sulfide has a composition corre- 
sponding approximately to a heptasulfide. The com- 
position of the polysulfide as well as its concentration 
in fresh Levinstein mustard depends upon the con- 
ditions under which the reaction was carried out, 
especially upon the ternperature and upon the rate 


of agitation, amount of seed charge, and rate of addi- 
tion of ethylene. Very likely many other factors, such 
as previous history of the sulfur monochloride, also 
have important effects. 

If there is no sulfur precipitated during the re- 
action, there must be a definite relationship between 
the composition of the polysulfide and its concen- 
tration, since one sulfur atom is produced each time 
a molecule of 6fs(i8-chloroethyl) sulfide is formed 
and this sulfur must nearly all be present as poly- 
sulfides. Thus the higher the sulfur content of the 
polysulfide, the lower need be its mole concentration. 
Table 1 illustrates this relationship. The sulfur and 
chlorine contents of all the mixtures before stripping 
are 33.5 per cent and 37.1 per cent, respectively, as 
required to correspond to one atom of sulfur per 
molecule of 6fs(i3-chloroethyl) sulfide with one atom 
of sulfur. The table lists other properties, based on 
theory, which the original mixtures should have. By 
making the assumption that H-HSs mixtures are 
produced by stripping it is possible to tabulate the 
final content by weight of each constituent and the 
sulfur and chlorine content of the resulting mixtures. 

The theoretical values which appear in the table 
are in excellent agreement with the vast quantity of 
experimental data on Levinstein mustard compiled 
at Edgewood Arsenal and other Chemical Warfare 
Service laboratories. Many of these data are sum- 
marized else where. 


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PRODUCTION PROCESSES FOR H, HQ, AND HT 


39 


6zs(i8-Chloroethyl) disulfide was formerly thought 
to be present in Levinstein H in amounts as high as 
6 per cent but methods which do not result in the 
degradation of higher poly sulfides indicate a much 
smaller percentage for this component. Analysis 
of the stripped nonhydrolyzable residue from Levin- 
stein H (composed of HS2 and HS5) and of the steam 
distillate from this (composed of HS2 and HS3) by 
comparison of their refractive indices with curves 
prepared from known mixtures indicate 1 to 1.8 per 
cent of HSo in crude Levinstein which is in good 
agreement with a value obtained by analysis of a 
fraction obtained by low- temperature molecular 
distillation of Levinstein 

In addition to the higher polysulfides, several 
other impurities are usually present in significant 
amounts in Levinstein H. Of these, one of the most 
important is l,2,2'-trichlorodiethyl sulfide (“trichloro 
H”). This material is formed by the chlorinating 
action of sulfur chlorides, particularly in processes 
where higher temperatures are encountered. The 
pressure instability of both Levinstein H and British 
sulfur dichloride mustards has been ascribed to the 
ready loss of hydrogen chloride from this and similar 
substances.^^’^^^ The product of dehydrohalogen a- 
tion, j8-chloroethyl j8'-chloro vinyl sulfide (CECVS), 
is thus also an impurity. 

Evidence for the presence of trichloro H in crude 
Levinstein H is mostly indirect but can be summa- 
rized as follows: 

1. Levinstein H contains an acidic impurity or an 
acid-forming impurity which is usually expressed as 
HCl, but which cannot be removed by air blowing 
as can HCl. 

2. Vacuum distillation of Levinstein H is accom- 
panied by a weight loss, at least a part of which is 
HCl. The main impurity in the distillate appears to 
be /3-chloroethyl /3'-chlorovinyl sulfide. 

3. Experiments on fractional melting of crude 
Levinstein H indicate that an impurity appearing in 
the first (lowest melting) fractions also appears in 
the distillate of such fractions. This does not indicate 
what the impurity is, but the inference is that 
i3-chloroethyl /3'-chlorovinyl sulfide is present in the 
distillates, whereas its precursor, trichloro H, is pres- 
ent in the original material. Semiquantitative esti- 
mates indicate that it may make up as much as 
6 per cent of the crude H.^^ 

Both trichloro H and i3-chloroethyl jS'-chlorovinyl 
sulfide have been synthesized, the latter by an un- 
ambiguous method making use of the addition of 


/3-chloroethylsulfenyl chloride to acetylene as well 
as by dehydrochlorination of trichloro H.^® 

In addition to the above impurities, Levinstein H 
contains varying small amounts of a number of 
other substances. Among these may be mentioned 
small amounts of volatile materials, including 
methane,®^ hydrogen chloride,®^ diethyl ether,®^ chlo- 
rinated hydrocarbons, possibly 2-chlorobutane or 
ethylene chloride,^^’^^ and sulfur. Levinstein H 
which has been prepared or stored in iron always 
contains dissolved iron in greatly varying amounts, 
depending upon the length and conditions of storage 
and the conditions of the original reaction. One of 
the actions of hexamine as a stabilizer is to remove 
this iron. 

The storage of Levinstein mustard in the presence 
of iron at 65 C leads to the formation of an iron- 
containing polymer. This polymer has been shown to 
be a sulfonium salt of 5fs(i8-chloroethyl) sulfide, 
dithiane, and ferrous chloride,^® arising by the fol- 
lowing mechanism: 

Ferrous sulfide is formed by the action of poly- 
sulfide on iron, 

Fe + HS. ^ FeS + HS(^_i) 

and the ferrous sulfide transforms mustard into di- 
thiane. 

FeS + CICH 2 CH 2 SCH 2 CH 2 CI — ^ 

CH 2 CH 2 

/ \ 

S S + FeCls 

\ / 

CH 2 CH 2 

This combines with mustard and the ferrous chloride 
to form the polymer 

CH 2 CH 2 

/ \ 

xS S + a;(ClCH2CH2)2S + x/2FeCl2-^ 

\ / 

CH 2 CH 2 

' cr + CH2CH2 

/ \ 

S S— CH 2 CH 2 SCH 2 CH 2 — 

\ / I 

CH 2 CH 2 FeCU jx 

Levinstein H which has been heated or which has 

undergone storage at elevated temperatures also 
contains small amounts of Q, dithiane, and ethylene 
chloride, formed by the following series of reaction: 


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40 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


2 CICH 2 CH 2 — S— CH2CH2CI ^ 

s+— ( ch 2 CH 2 CI )2 + cr ^ CICH 2 CH 2 — Cl 

I 

CH2 + (C1CH2CH2-S-CH2)2 

I 

CH2 

I 

S— CH2CH2CI 

(CICH2CH2S— CH2)2 — > 

CH2— CH2 

/ \ 

CICH 2 CH 2 — s+ s + cr — > 

\ / 

CH 2 — CH 2 

CH 2 — CH 2 

/ \ 

CICH2CH2CI + s s 

\ / 

CH2— CH2 

The presence of Q in stored Levinstein was inde- 
pendently indicated by a series of toxicological ob- 
servations on the increased vesicancy of samples of 
H stored at 65 C and above, 

5.2.5 The Mechanism of Formation of 
Levinstein H 

Any mechanism which is proposed to account for 
the formation of Levinstein mustard must explain 

1. The formation of 6fs(j8-chloroethyl) sulfide. 

2. The formation of polysulfides derived from the 
linear HS3 skeleton. 

3. The absence of more than traces of the disul- 
fide. 

4 . The absence of more than traces of free sulfur. 
A mechanism which fulfills these corditions has been 
developed. 

There is chemical and physical evidence to sup- 
port the assumption that .sulfur monochloride dis- 
proportionates, to a slight extent at least, to give 
!<ulfur dichloride and sulfur tritadichloride according 
to equation (3). 

2 S 2 CI 2 ^ SCI2 + S3CI2 K3) 

It is beyond the scope of this review to discuss this 
evidence, but, if this equilibrium exists, then it is 
po.ssible for all three materials to react with ethylene 
according to equations (4), (5), and (6). 

2C2H4 H- SCI2 CICH2CH2SCH2CH2CI ( 4 ) 
2C2H4 + S2CI2 — ^ CICH2CH2SSCH2CH2CI ( 5 ) 
2C2H4 4- S3CI2 ^ CICH2CH2SSSCH2CH2CI (6) 


Equation (6) would apply equally well if higher 
polythio sulfur chlorides such as S4CI2, etc., were 
formed. 

The disulfide (HS 2 ) produced according to equa- 
tion (5) has been shown to react readily with sulfur 
monochloride to produce jS-chloroethyl.sulfenyl chlo- 
ride and sulfur tritadichloride according to equa- 
tion (7).^® 

CICH2CH2SSCH2CH2CI -h3S2Cl2— > 

2 CICH 2 CH 2 SCI -h 2 S 3 CI 2 (7) 

These products can react with ethylene rapidly to 
yield 6fs(/3-chloroeth3d) sulfide and HS3, or, in the 
reaction used to demonstrate the pre.sence of the 
sulfenyl chloride, with cyclohexene to yield /3-chloro- 
ethyl (8'-chlorocyclohexyl sulfide. 

CICH2CH2SCI -h C2H4 — ^ CICH2CH2SCH2CH2CI 

(8) 

The series of reactions corresponding to equations 
(5), (7), and (8) are reminiscent of the mechanism 
originally proposed by Conant in 1920. According 
to Conant, the reaction passed through the following 
phases : 

S2CI2 ^ S + SCI2 

C2H4 -f SCI2 — ^ CICH2CH2SCI 

C2H4 -f CICH2CH2SCI — > CICH2CH2SCH2CH2CI 

These reactions were accompanied by a secondary 
reaction 

2 CICH 2 CH 2 SCJ -f 7?S ^ (ClCH 2 CH 2 ) 2 Sn + S 2 CI 2 

Convincing evidence of either the existence of 
/3-chloroethylsulfenyl chloride or its participation in 
the reaction was not advanced until 1943 when 
the pure material was prepared by chlorinolysis of 
HS 2 and HS 3 . It reacts very readil}" with ethylene 
and with cyclohexene to produce H and /3-chloroethyl 
/3'-chlorocyclohexyl .sulfide, respectively. jS-Chloro- 
ethylsulfenyl chloride also appears to be formed by 
the action of .sulfur monochloride on HS 2 and by the 
action of sulfur dichloride on HS 2 and HS 3 , since 
j(3-chloroethyl j3'-chlorocyclohexyl sulfide can be ob- 
tained by the addition of cyclohexene to these re- 
action mixtures4^ 

As additional evidence that jS-chloroethylsulfenyl 
chloride is an intermediate in the Levinstein reaction, 
it has been shown that an equimolecular mixture of 
ethylene and cyclohexene vapor used in the Levin- 
stein proce.«s instead of pure ethylene produces, in 
addition to fefs(iS-chloroethyl) sulfide and his-2- 
chlorocyclohexyl sulfide, the mixed sulfide, jS-chloro- 


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PRODUCTION PROCESSES FOR H, HQ, AND HT 


41 


ethyl 2-chlorocyclohexyl sulfide in the expected mole 
ratio of approximately 1/ 1/2 respectively. Likewise, 
an equimolar mixture of ethylene and cyclohexene 
vapor passed through a solution of sulfur dichloride 
in mustard yields the same three products, indicat- 
ing the two-step nature of the reaction of ethylene 
with sulfur di chloride. 

The HSa formed according to equation (6) has 
been shown to be sulfurized readily at 30-35 C by 
sulfur monochloride to higher polysulfides [equations 
(9), (10), and (11)] and again sulfur dichloride is the 
other product of the reaction. It immediately reacts 
with ethylene to produce more 6fs-j(3-chloroethyl 
sulfide. 

HSs + S2CI2 HS4 + SCI2 (9) 

HS4 + S2CI2 — ^ HSs + SCL (10) 

HS5 + S2CI2 — ^ HSe + SCI2, etc. (11) 

Because sulfur dichloride is introduced into the re- 

action mixture as a product of other reactions or as a 
result of the initial equilibrium, and since it reacts 
rapidly with ethylene, its concentration is low as long 
as excess ethylene is present. For this reason, the 
problem of overchlorination with resulting pressure 
instability of the product is not so significant in the 
Levinstein process as in the processes involving the 
use of sulfur dichloride directly. 

The net result of this series of reactions is to pro- 
duce a mixture of 6fs-/3-chloroethyl sulfide and poly- 
sulfides corresponding to the monosulfide. The 
overall equation for the Levinstein reaction, (12), is 
thus : 

2a:C2H4 + xS2C\2—^(x - 1)C1CH2CH2SCH2CH2C1 
+ (C1CH2CH2)2S, + i (12) 

The amount of impurity (as poly sulfides) in the re- 
sulting Levinstein mustard depends upon the rate of 
formation of HS3 and on the rate of sulfurization 
of HS3 by sulfur monochloride. 

If it is assumed that the effect of temperature on 
this series of reactions is to increase the rate of all 
the reactions but that this is partiallj^ offset by the 
decreased solubility of ethylene at higher tempera- 
tures, then the net effect is to increase the rate of the 
sulfurization reactions relative to those involving 
ethylene. As fast as HS3 molecules are formed, they 
are sulfurized to higher polysulfides, and, since the 
addition of each sulfur atom results indirectly in 
the formation of one molecule of H (through SCI2), 
the product formed at higher temperatures should be 
high in H content and in very high unstable poly- 


sulfides which readily lose sulfur. At low tempera- 
tures sulfurization is slower, more HS3 is formed, it 
is sulfurized to a lower degree, and less H results. 
This interpretation is in excellent agreement with 
the known characteristics of high-temperature (60 
C process) and low-temperature (Levinstein proc- 
ess) H. 

The reaction of sulfur monochloride with propylene 
to give “propyl mustard,” long believed and now 
known to have the “normal” CH 3 CH(C 1 )CH 2 
— S — CH2CH(C1)CH3 rather than the “iso” struc- 
ture, can also be accommodated to the above 
reaction scheme, since it has been shown that /3- 
chloroethylsulfenyl chloride, and by inference other 
sulfenyl chlorides, add to propylene in accordance 
with Markownikoff’s rule to give the “normal” struc- 
ture. 

It should be noted that even if the initial assump- 
tion of the scheme, i.e., the disproportionation of 
sulfur monochloride to sulfur dichloride and sulfur 
tritadichloride is not valid, the following series of 
reactions provide a satisfactory mechanism : 

2C2H4 + S2CI2 CICH2CH2— S— S— CH2CH2CI 

( 13 ) 

CICH2CH2— S— S— CH2CH2CI + 3S2CI2 

2 CICH 2 CH 2 SCI + 2 S 3 CI 2 (or 2S + 2 S 2 CI 2 ) (14) 

CICH2CH2SCI + C2H4 

CICH2CH2— S— CH2CH2CI ( 15 ) 
S3CI2 (or S + S2CI2) + 2 C 2 H 4 — > 

CICH2CH2SSSCH2CH2CI ( 16 ) 
2CICH2CH2SCI + 2S3CI2 — > 

CICH2CH2SSSCH2CH2CI + SCI2 + 2S2CI2 ( 17 ) 

2C2H4 + SCI2 CICH2CH2SCH2CH2CI ( 18 ) 

Sulfurization of HS3 to higher polysulfides by sul- 
fur monochloride with the simultaneous prodifction 
of H would proceed as already described. 

The assumption that sulfur dichloride can react in 
both linear and angular forms to give linear disul- 
fides and thiosulf oxides is not considered likely, since 
it has not been possible to isolate a thiosulf oxide or 
to obtain convincing evidence of the existence of this 
type of compound. The possibility cannot be ex- 
cluded, however, since in one case it has been 
possible to isolate material of composition correspond- 
ing to a monosulfide plus varying amounts of sulfur 
which appeared to be present in a very labile 
form.^^ '^^ Evidence that trisulfides also exist in the 
linear form has been summarized. 


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42 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


5.2.6 The Purification and Stabilization 
of Levinstein H 

The storage and corrosion stability of Levinstein H 
as ordinarily produced is not entirely satisfactory 
and it cannot be thickened for use as a spray. A re- 
view of the immense amount of effort which has been 
devoted to the study of its stabilization is beyond the 
scope of this report, and it is possible here only to 
describe the present position. 

A number of methods have been examined for the 
purification of Levinstein H, including treatment 
with ammonia, heat treatment, treatment with silica 
gel or charcoal, distillation under various pressures, 
flash distillation, carrier distillation using both steam 
and organic liquids, solvent extraction, and crystal 
fractionation. Of these, only vacuum distillation, 
steam distillation, and solvent extraction appear 
feasible for use on a plant scale. Pilot plant studies 
of all three have been carried out.2®'*®’i®0’254 with- 
out a detailed discussion of the advantages and dis- 
advantages of each method, it can be said that 
solvent extraction using commercial pentane gives ex- 
cellent recovery (up to 95 per cent of the available H) 
of a product which contains 92.5 per cent H but 
whose pressure and corrosion stability is inferior to 
that of steam- or vacuum-distilled material; super- 
heated steam distillation which requires acid-proof 
equipment produces more stable material of 95 per 
cent or better purity in recoveries of 80 per cent; 
whereas vacuum distillation of water-washed Levin- 
stein H produces material of exceptionally good sta- 
bility and 95-96 per cent purity with 86 per cent 
recovery. The vacuum distillation has the advantage 
of using existing plant facilities and appears to be 
the method of choice. Washing with water removes 
iron salts and acid and is an essential step; vacuum 
distillation of unwashed Levinstein H is unsatis- 
factory as a purification measure. 

A detailed description of the efforts to improve the 
pressure and corrosion stability of Levinstein H and 
to retard its decomposition without resorting to ex- 
tensive purification procedures cannot be given here. 
As a result of these efforts, which have included stud- 
ies on a variety of stabilizers, the addition of 1 per 
cent of hexamethylenetetramine (hexamine), whose 
efficacy as a stabilizer for Levinstein H was first 
recognized by the CWS-MIT Development Labora- 
tory,®'* to all munitions charged with Levinstein H 
and to all storage containers is now standard. This 
treatment confers satisfactory storage stability, as 
regards decomposition, corrosion, and pressure de- 


velopment, on Levinstein H, but is not sufficient to 
render this mustard satisfactory for thickening with 
polymethylmethacrylate. For this purpose it is 
necessary to use Levinstein H whose iron content is 
below 1 per cent, to add 1 per cent hexamine and 
2 per cent nitrogen bases (either coal tar or petro- 
leum), and to store the thickened material in lac- 
quered containers.2'*®2,87,89,9o,ii4,i43,i52 

The stability of Levinstein mustard which has 
been purified by various methods is also improved by 
the addition of 1 per cent hexamine. 

The precipitate formed when hexamine is added to 
Levinstein H contains hydrogen chloride, iron chlo- 
rides, and sulfur. The action of hexamine as a stabi- 
lizer appears to be due to its ability to reduce iron 
content and acid, and has been ascribed to these 
factors and to its high stability and low basicity, 
which was believed to be responsible for its lack of 
compound formation with H.®2 There is, however, 
disagreement as to the solubility of hexamine in H 
and as to the extent of compound formation between 
hexamine and H,®2-i52 ^nd the mechanism of stabi- 
lization of Levinstein H by hexamine cannot be con- 
sidered completely clear. 

No attempt will be made here to describe the ex- 
tensive work on the thickening of H for use as an 
airplane spray or in airburst munitions. This subject 
is treated in detail elsewhere.® 

5.2.7 Photosynthetic Methods for the 
Preparation of H and Analogs 

As a result of work initiated in 1942 under Divi- 
sion 9 of NDRC, a novel method for the synthesis of 
H and particularly of more complex relatives of H, 
such as Q, has been developed. The method gives 
excellent yields, is capable of great flexibility, and 
has been applied successfully in a number of cases 
(see Table 2 ).®** 277 synthesis consists of the 
photochemical addition of hydrogen sulfide or mer- 
captans to vinyl chloride and related olefins in the 
presence of photoactivators. 

The addition of h 3 ^drogen sulfide to vinyl chloride 
brought about by irradiation with ultraviolet light 
in the presence of peroxide catalysts was accom- 
plished in 1942 by NDRC groups but a publication 
appearing about this time indicates that the process 
had been studied earlier by a private group. 2 ^^ Yields 
of 75-80 per cent accompanied by some j8-chloro- 
ethylmercaptan and polymeric material can be ob- 


® See NDRC Division 1 1 Summary Technical Report. 


SECRET 


PRODUCTION PROCESSES FOR H, HQ, AND HT 


43 


Table 2. Compounds related to H prepared by photo- 
synthetic methods. 


Compound Reference 


1. /3-Chloroethyl ethyl sulfide 59 

2. hfs(/3-Chloroethyl) sulfide (H) 59 

3. /3-Chloroethyl /3', /3'-dichloroethyl sulfide 

(2-chloro H) 42 

4. /3-Chloroethyl /3'-hydroxyethyl sulfide (CH) 43,142 

5. )3-(j8-Chloroethylthio)ethylmercaptan 125 

6. l,2-6fs(/3-Fluoroethylthio)ethane 59 

7. l,2-5fs(/3-Chloroethylthio)ethane (Q) 59, 122etseq. 

8. l,2-6fs(/9-Bromoethylthio)ethane 59 

9. l,3-52s(/3-Chloroethyl)-2-chloropropane 59 

10. l,2-6fs(/3-Chloroethyl)-3-hydroxypropane 59 

11. 2,3-6zs(/3-Chloroethyl)butane 59 

12. 6fs(/3-Chloroethylthioethyl) ether (T) 59, 131 

13. 5is(/3-(/3-Chloroethylthio)ethyl) sulfide (di H) 129 

14. a, a'-6?s(/S-Chloroethylthio)-p-xylene 59 

15. d-Fluoroethyl thiolacetate 59 


tained. Illumination with ultraviolet light in the 
region 2 , 800 - 3,200 A is effective; peroxides and ben- 
zoin, a known photoactivator in the ultraviolet, pro- 
mote the reaction. Neither thermal nor catalytic 
activation will induce addition.^® 

It has been shown that the photochemical addi- 
tion of hydrogen sulfide to olefins proceeds according 
to Markownikoff’s rule. Ultraviolet light alone was 
found to be sufficient for the reaction to take place, 
but photosensitizers extended the range of effective 
frequencies. In the case of the synthesis of H from 
hydrogen sulfide and vinyl chloride, both irradiation 
with ultraviolet light and the presence of a catalyst 
appear to be necessary.^® 

The feasibility of synthesizing pure Q in high 
yields by the photochemical addition of ethane- 
dithiol to vinyl chloride has been demonstrated 
and the reaction has been exhaustively studied at 
Edge wood Arsenal. 

The reaction is carried out as a batch process, and 
on a laboratory scale can be done either under at- 
mospheric pressure at the boiling point of vinyl 
chloride (— 13 . 6 C) or at room temperature under 
approximately 4 atmospheres. Yields are 90 per cent 
in the first case and quantitative in the second when 
the irradiation is supplied by an S -4 General Electric 
mercury vapor lamp and either benzoyl peroxide or 
sodium percarbonate is present. The reaction can 
also be carried out at room temperature by bubbling 
vinyl chloride through the reaction mixture. Re- 
sults at 75 C have been definitely inferior to those 
obtained at lower temperatures.^'*^ The presence of a 
solvent such as benzene is advantageous since vinyl 
chloride is not very soluble in ethanedithiol.*^®’*'*^ 


Methanol can also be used but the product separates 
from this solvent as a second phase containing both 
methanol and ethanedithiol, and must be stripped. 
The possibility of using methanol in a continuous 
system has been recognized,***^ but no development 
work along this line has been reported. 

The Q produced is of excellent quality and melts 
at 53.6 C,* 2 ^ but has a pronounced odor of ethane- 
dithiol, which may be removed by treatment with 
arsenic trichloride or L.*^^ 

The heat of the photochemical reaction, which is 
exothermic, has not been measured but calculations 
from bond energies indicate a value of about 18 
kcal/mole.*22 

In contrast to the addition of hydrogen sulfide to 
vinyl chloride, the addition of ethanedithiol proceeds 
without promoters or photosensitizers. However, 
the presence of these is very desirable and a number 
have been examined, particularly with respect to the 
reduction of the light requirements of the reaction. 
The most effective are peroxides of various types and 
disulfides. Diphenyl disulfide is far superior 
to any of 18 other disulfide catalysts tried when the 
reaction is carried out in sealed tubes, but is no better 
than diamyl disulfide when used at atmospheric 
pressure. Oxygen is ineffective.*^® 

The reaction appears to proceed by a chain mech- 
anism initiated, in the uncatalyzed case, by the 
photodissociation of ethanedithiol into radicals 
which attack the vinyl chloride molecule. Quantum 
efficiencies of about 1,000 are observed. *^^ Chain 
propagation occurs through the alkyl sulfide rad- 
ical: 


HS— CH2CH2— SH ^ HS— CH2CH2— S- + H- 

HS— CH2CH2— S- + CH2=CH— Cl — ^ 

HS— CH2CH2— S— CH2CH— Cl 

HS -CH2CH2— S— CH2CH— Cl 

/HS— CH2CH2— SH \ 

lor HS— CH2CH2— S— CH2CH2CI/ 

HS— CH2CH2— S— CH2CH2CI 

/HS— CH2CH2— S- / 

(or -S— CH2CH2— S— CH2CH2— Cl/ 

•S— CH2CH2— S— CH2CH2CI + CH2=CHCI 

— > Cl— CH2CH2— S— CH2CH2— S— CH2CHCI 

CICH2CH2— S— CH2CH2— S— CH2CH— Cl + 

HS— CH2CH2— SH ^ Q + HS— CH2CH2— S, etc. 

In the case of catalysis by photosensitizers, the initial 
photodissociation is of the catalyst molecule, and the 


SECRET 


44 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


radical formed initiates a radical chain similar to the 
one above. Thus, the problem of reducing the light 
requirements of the reaction is resolved into one of 
finding photosensitizers which will yield radicals at 
longer wavelengths than that required for the 
photodissociation of ethanedithiol.^ Disulfides absorb 
light even more strongly than ethanedi thiol in the 
near ultraviolet, and provide alkyl sulfide radicals at 
longer wavelengths. Thus the 3,650 A mercury line 
is effective if diamyl disulfide is used as a photo- 
sensitizer in the Q reaction. The diaryl disulfides, 
which are known to be easily dissociable, absorb 
at even longer wavelengths (up to 4,200 A for di- 
phenyl disulfide) and are the most effective photo- 
sensitizers. Thus with diphenyl disulfide, which has 
been thoroughly investigated, excellent conversions 
are obtained with 300-watt Mazda lamps, and fairl}^ 
good conversion is possible even with a 60-watt 
Mazda lamp. Among other easily dissociable com- 
pounds examined, the triaryl free radicals did not 
prove to be effective promoters. 

A novel “ionic chain’’ mechanism for this reaction 
received serious early consideration by CWS work- 
ers but was later abandoned. An early view that 
vinyl chloride was activated by light was similarly 
abandoned, since vinyl chloride does not absorb in 
the ultra violet. 

Substances normally effective in acid-base cata- 
lyzed reactions such as boron trifluoride, phosphoric 
acid, hydrogen ion, triethanolamine, and water are 
ineffective as promoters iu the photosynthesis 

of Q.135.147 

A number of materials, e.g., copper, iron, tin, 
carbon, sulfur, and polysulfides, exert an inhibiting 
effect on the reaction, in some cases enough to com- 
pletely prevent reaction,^® and considerable diffi- 
culty has been experienced in scaling up the reaction 
because of this sensitivity to inhibition. Laboratory 
results indicate that stainless steel, aluminum, lead, 
zinc, and silver are not injurious. 

The ethanedi thiol required in the photosynthesis 
of Q can be prepared in 76 per cent yield by thiona- 
tion of ethylene chloride with aqueous sodium sulf- 
hydrate under hydrogen sulfide pressure. On a semi- 
plant scale, the expensive hydrogen sulfide has been 
replaced by carbon dioxide, which produces hydrogen 


^ The uncatalyzed addition of ethanedithiol to vinyl chlo- 
ride occurs at wavelengths of 3,125 A and at all wavelengths 
below this, in fair agreement with a probable threshhold wave- 
length (calculated from bond strengths) of 3,254 A for the 
photodissociation of ethanedithiol. 


sulfide from the sodium sulfhydrate.^® The efficiency 
of this process for production of ethanedithiol on a 
small-scale manufacturing basis has been demon- 
strated by the production of about 1,600 lb. The con- 
ditions were not studied exhaustively, but a cheap, 
practical process easily adaptable to large-scale man- 
ufacture was developed.^® 


5.3 TABULATION OF ORGANIC SULFUR 
COMPOUNDS EXAMINED AS CANDIDATE 
CHEMICAL WARFARE AGENTS 

The many analogs of H which have been studied 
b}^ investigators in the United States, Great Britain, 
and Canada are listed in Table 3, with references to 
the reports on their preparation and toxicological 
action. The closely related nitrogen mustard series is 
tabulated in Chapter 6. It can be stated that the 
study of analogs in the sulfur mustard series has not 
disclosed compounds superior to H, Q, and T in po- 
tential general usefulness as chemical warfare agents. 
In the study of the mechanism of action of agents in 
this category, however, as will be noted later, ex- 
tensive use has been made of the data on the chemical 
and toxicological properties of the compounds re- 
lated to H. 


5.4 PROPERTIES OF H, Q, AND T 

5.4.1 Physical Properties 

The physical properties of H, Q, and T which have 
the most direct bearing on the effectiveness of these 
agents as war gases are the following: 


Density (liquid) 
g/ml at 25 C 
Boiling point C 
Freezing point C 
Volatility 
mg/1 25 C 


H Q 

1.27 

217 353 (calc. )'4 

14 56-571* 

0.96'»<* 0.000496 


T 

1 24231 

120/0.02 mm23i 
10231 

0 . 002866 ® 


Whereas H has sufficient volatility to yield injuri- 
ous vapor dosages, neither Q nor T presents vapor 
hazards. The vesicant action of Q and T depends 
upon contact between the skin and the liquid or 
particulate agent. The low volatility of these two 
compounds gives them a much longer persistence 
than H as potential hazards on contaminated 
terrain. 


SECRET 


TABULATION OF ORGANIC SULFUR COMPOUNDS 


45 


Table 3. Organic sulfur compounds examined as candidate chemical warfare agents. f 


The general arrangement of the table is as follows: (1) mercaptans and derivatives; (2) sulfides and sulfide ethers; 
(3) polysulfides; (4) sulfoxides; (5) sulfones; (6) derivatives of thioacids; (7) sulfonium salts; (8) derivatives of sulfinic 
and sulfonic acids; (9) sulfur compounds of unknown constitution. 

The following abbreviations are used: nD^ refractive index at t C; specific gravity at b C in reference to water at 
to C; mp, melting point in C; bpp, boiling point in C at p mm Hg; vp‘, vapor pressure in mm Hg at t C; and voh, satu- 
ration concentration (volatility) in mg/1 at / C. 

Centigrade scale is used throughout the table. 



Reference 

to 


Physical properties 

Reference to 
toxicity 

Compound 

synthesis 

Property 

Reference 

data 

1. |S-Fluoroethylmercaptan 

59 

bp225 

38.5° 

59 

34 



riD"® 

1.4290 

59 

. . . 

2. /3-Chloroethylmercaptan 

16, 53 

bp760 

114-120° 

16 

34, 54 

3. |8-Hydroxyethylmercaptan 

16 

bp^ 

47-50° 

16 

. . . 

4. 1 ,3-Dichloro-2-mercaptopropane 

61d 




34, 54 

5. 3-Mercapto-l, 2-propylene sulfide 

14 



. . . 

34 

6. Ethanedithiol 

29, 58 

bp®° 

65-68° 

58 

34 


. . . 


1.5570 

58 

. . - 




1.1182 

58 


7. l-Chloro-2,3-dimercaptopropane 

8. l-Hydroxy-2,3-dimercaptopropane* 



— 


34, 54 

(DTK) (BAL) 

14, 15, 237 

bpi® 

115°±1 

14 

242b 




1.570-1.573 

14 





1.238-1.240 

14 


9. 2,3-Dimercaptopropionic acid 

. . . 




34 

10. 6fs(/S-Mercaptoethyl) sulfide 

1 1 . 1 ,6-Hexanedithiol 

12. o-Aminothiophenol* 

13. 2-(w-Chloroacetamino)-5-methyl-thiophenol* 

14. Trichloromethyl sulfenyl chloride* 

8 

bp3 

104-106° 

8 

34, 54 

(perchloromethyl mercaptan) 

271 

bp7G0 

148-149° 

278 

247 


. . . 

bp^” 

CO 

o 

278 



. . • 

d^ 

1.722 

278 




vol-” 

18 

278 


15. /3-Chloroethylsulfenyl chloride 

35 

bpi® 

47-47.5° 

35 

34, 54 

16. o-Xitrobenzenesulfenyl-6fs(/3-chloroethyl)amine 

39 

mp 

104-105° 

39 

34 

17, 6fs(/3-Chloroethylmercapto) chloramine 

61c 

.... 



34 

18. Sulfilimine of chloramine-T and H 

65a 

mp 

144.6° 

278 

34 

19. ^e<raA:fs-jS-Chloroethylmercaptosilicon 

61 h 

bpi-2 

98° 

61h 

34 




1.390 

61h 


20. Tributylthioethoxy tin 

5 

bpi ^ 

126° 

5 





1.132 

5 


21, Triethyl /3-chlorothioethoxy lead 

61d 




34 

22. Thallous /8-chloroethylmercaptide 

23. 6fs(a-Chloromethyl) sulfide* 

61f 

mp 

>300° 

61f 


24. Methyl /3-chloroethyl sulfide 

11, 23 

bp‘*3 

52-53° 

11 

34, 54, 247 



vopo 

32.7 

38 


25. /3-Hydroxyethyl methyl sulfide 

23 

bpi2 

63-66° 

23 


26. a-Chloromethyl-jS'-chloroethyl sulfide 


bpi^ 

105° 

247 

247 

27. 3-Chloro-l, 2-propylene sulfide* 

8 

bp^“^ 

38-40° 

8 

34, 54 




1.5127 

8 



. . . 

dxd^ 

1.250 

8 


28. 3-Thiocyano-l, 2-propylene sulfide 

29. Methyl 2,2'-dichloroisopropyl sulfide* 

30. Methyl 2,2'-dihydroxyisopropyl sulfide* 

31. Divinyl sulfide* 

32. 6fs-Hexachlorodivinyl sulfide 

33. j8-Chloroethyl vinyl sulfide* 

53 




34 

34. /3-Chloroethyl-af-chlorovinyl sulfide* 





189 


* Not all the British reports concerning compounds marked with an asterisk are available in this country. References are contained in refer- 
ence 176. 

t The table includes sulfur compounds in which sulfur is linked to carbon with the exception of thiocyanates, which are included in Table 1, 
Chapter 14. Sulfur compounds containing either arsenic or phosphoras are included in Table 1, Chapter 7, and Table 1, Chapter 9, and have 
not been repeated here. 


SECRET 


46 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


Table 3 {Continued). 





Compound 

Reference 

to 

synthesis 

Physical properties 
Property Reference 

Reference to 
toxicity 
data 

35. /3-Chloroethyl /3'-chlorovinyl sulfide* 

35 

bpo.75 

46° 

35 

34 



bp0.15 

30° 

35 




mp 

-24° 

35 


36. Equimolar-mixture of triethylphosphorus and 



1.5480 

35 


diethyl sulfide 

61b 





37. Ethyl /3-chloroethyl sulfide* 

53, 59 

bp43.5 

73-76° 

59 

34, 54 




1.4858 

59 




VOp« 

16.57 

38 


38. /3-Thiocyanodiethyl sulfide* 

39. /3-Chloroethyl /3'-fluoroethyl sulfide 






64a 

bp3o 

91.5-92.5° 

64a 

34, 54 



mp 

-44° 

64a 





1.4872 

64a 





1.228 

64a 


40. 6ts(a-Chloroethyl) sulfide* 

8 

bpi5 

58.5-59.5° 

8 


41. a-Chloroethyl jS-chloroethyl sulfide* 






42. Mustard gas 

43. /3-Chloroethyl /3',j8'-dichloroethyl sulfide 

See text 


See text 


See text 

(2-chloro H) 

42 

bpO.05 

68-69° 

42 

34 




1.5380 

42 


44. 6ts()3,/8'-Dichloroethyl) sulfide* 






45. 6ts(a,j9,/3'-Trichloroethyl) sulfide* 






46. 5ts(iS-Bromoethyl) sulfide 

53 

bpo-^ 

91-93° 

53 

34, 54, 247 



mp 

31-33° 

53 


47. 6ts(/3-Iodoethyl) sulfide 


mp 

68-70° 

247 

247 

48. /3-Chloroethyl j3'-cyanoethyl sulfide* 






49. 6ts(/3-Cyanoethyl) sulfide* 

50. /3-Chloroethyl /3'-hydroxyethyl sulfide* (CH) 






8, 43, 142 

bpO.6 

100° 

43 




?lD^“ 

1.5188 

43 


51. 6ts(iS-Hydroxyethyl) sulfide 

Commercial 




34 

52. 6ts(/3-Chloroformylethyl) sulfide 

64a 




34 

53. 6ts(/3-Chloroacetoxyethyl) sulfide* 






54. 5ts(/8-Trichloroacetoxyethyl) sulfide* 






55. 5ts(j8-Bromoacetoxyethyl) sulfide* 






56. jS-Hydroxyethyl /3'-cyanoethyl sulfide 

61e 

bpi9 

186-188° 

61e 





1.5101 

61e 





1.143 

61e 


57. /3-Chloroethylthioacetyl chloride* 






58. Ethyl /3-chloroethylthioacetate* 






59. Thiodiglycolic acid 

276 

mp 

129° 

276 

34 

60. Methyl thiodiglycolate 

11 

bp2 

102-104° 

11 





1.4748 

11 





1.230 

11 


61. Allyl /3-chloroethyl sulfide* 

53 

bpi4 

64.5-65° 

53 

34, 243c 



vop*’ 

6.63 

38 


62. Ethyl /3-chloropropyl sulfide* 






63. Ethyl /3, 7-dichloropropyl sulfide* 






64. jS-Chloroethylpropyl sulfide* 





243c 

65. jS-Chloroethyl /8'-chloropropyl sulfide* 

66. jS-Chloroethyl /3',7'-dichloropropyl sulfide* 

67. p-Aminophenyl-(7-chloropropylthio)ethylamine 

41 




54, 189 






hydrochloride* 






68. Acetonyl /3-chloroethyl sulfide 

53 

bpO.75 

76-85° 

53 




mp 

145-146° 

53 


69. /3-Chloroethylbutyl sulfide* 





243c 

70. /3-Chloroethyl a:'-methyl-/3'-chloropropyl sulfide* 






71. 5ts(Chloroallyl) sulfide* 






72. 6is(7-Chloroallyl) sulfide* 







Not all the British reports concerning compounds marked with an asterisk are available in this country. References are contained in refer- 


SECRET 


TABULATION OF ORGANIC SULFUR COMPOUNDS 


47 


Table 3 {Continued). 


Compound 

Reference 

to 

synthesis 

Physical properties 
Property Reference 

Reference to 
toxicity 
data 

73. 6ts(j8-Bromoallyl) sulfide* 






74. bts(/8-Chloropropyl) sulfide* 

41 

bp0.04 

107-108° 

41 

34, 54 

(propyl mustard) 



1.4903-1.4917 



75. his{ 7 -Chloropropyl) sulfide* 

8 

bp^ 

111-112° 



76. 6ts(i8, 7 -Dichloropropyl) sulfide* 






77. Propyl /3-hydroxy-7-fluoropropyl sulfide 

64e 

bp22 

105-107° 

64e 

34 

78. 6ts(s-Dichloroisopropyl) sulfide 





34, 54 

79. 6ts(a-Chloro-a-acetoxyisopropyl) sulfide* 






80. 6is(j8-Chlorobutyl)-3-sulfide 

Commercial 




34, 54 

81 . /S-Chloroethyl 2-chlorocyclopentyl sulfide 

53 

bp0.16 

73° 

53 

34 




1.5336 

53 


82. Ethyl 2,4,6-trichlorophenyl sulfide* 






83 . p-Ethylthiophenyldichlorostibine * 






84. /3-Chloroethylphenyl sulfide* 






85. jS-Chloroethyl o-nitrophenyl sulfide 

53 

mp 

50° 

53 

34, *54 

86. |8-Chloroethyl p-nitrophenyl sulfide 

87. l-/3-Chloroethyltliio-2,4-diaminobenzene hydro- 

53 

mp 

62° 

53 

34, 54 

chloride* 






88. p(/3-Chloroethylthio)phenyldichlorostibine* 






89. jS-Chloroethylcyclohexyl sulfide 

61f 

bp*° 

161-163° 

61f 

34, 54 

90. /3-Chloroethyl jS'-chlorocyclohexyl sulfide* 

35, 53 

bpo-^ 

108-109° 

53 

34 




1.5382 

53 


91. Reaction product of butadiene and sulfur di- 


vopo 

0.0474 

38 

... 

chloride 






92. 6is(a-Methyl-/3-chloropropyl) sulfide* 

182 

bp® 

o 


182 

93. 6ts[a-(Chloroaceto)-/3-chloroethyl] sulfide* 






94. /3-Chloroethyl heptyl sulfide* 





243c 

95. iS-Chloroethyl p-tolyl sulfide 

53 

bp2 

115° 

53 

34 




1.5728 

53 


96. /3-Chloroethyl benzyl sulfide 

53 

bpO.05 

95-97° 

53 

34, 243c 



VOpO 

0.115 

38 


97. /3-Chloroethyl nonyl sulfide* 





243c 

98. Diphenyl sulfide* 






99. 6ts(/8-Chlorocyclohexyl) sulfide* 

53 

mp 

73.5° 

53 

34 

100. jS-Chloroethyl undecyl sulfide* 





243c 

101. /3-Chloroethyl chloromethoxymethyl sulfide* 






102. /3-Hydroxyethyl chloromethoxymethyl sulfide* 






1 03 . 1 -Methoxy-2-( /3-chloroethy Ithio )ethane * 





243c 

104. l-Methylthio-2-(j8-chloroethylthio)ethane* 





243c 

105. 6ts(/8-Chloroethylthio) methane* 

53 

mp 

31-32° 

53 

34, 54 

106. 2-Methyl-4-chloromethyl-l,3-dithiocyclopentane* 






107. l-(/3-Chloroethylthio)-2-ethoxyethane* 





243c, 189 

108. l-(/3-Chloroethoxy)-2-(j8-chloroethylthio)ethane* 


bpi 

120° 

179 

179 

109. l-(/3-Chloroethylthio)-2-ethylthioethane* 





243c 

1 10. l,2-6is(/3-Fluoroethylthio)ethane 

59 

cr 

85° 

59 


111. l,2-6is(j8-Chloroethylthio)ethane* (Q) 

See text 

mp 

54° 

59 

See text 

112. l,2-6ts(/3-Bromoethylthio)ethane 

53, 59 

mp 

78-79° 

53 

34, 54 

113. l,2-6is(j8-Cyanoethylthio)ethane* 






1 14. l,2-6ts(/3-Hydroxyethylthio)e thane* 






115. l,2-6ts(/3-Chloroethy Ithio) acetaldehyde* 

116. 2,2-Dimethyl-4-chloromethyl-l,3-dithiocyclo- 






pentane* 





243c 

117. l-(/3-Chloroethylthio)-2-propoxyethane* 





243c 

1 18. l-(j8-Chloroethylthio)-2-propylthioethane* 





243c 

1 19. l,2-6ts(/3-Chloroethylthio)propane 

”8 

bpO.5 

139-142° 

8 

34, 54 




1.233 

8 


120. 2,3-6ts(/3-Chloroethylmercapto)-l-chloropropane 

59 




34 

121. l,3-5ts(/3-Chloroethylthio)propane* 

53 

bp0.02 

101° 

53 

34, 54 


* Not all the British reports concerning compounds marked with an asterisk are available in this country. References are contained in refer- 
ence 176. 


SECRET 


48 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


Table 3 {Continued) . 


Compound 


Reference 

to 

synthesis 


Physical properties 
Property Reference 


Reference to 
toxicity 
data 


1 22 . 2,2-bis{ /3-Chloroethylt hio )propane * 

123. 2-Chloro-l,3-6is(j8-chloroethylthio)propane 

124. 2,3-6is(/3-Chloroethylmercapto)propanol 

125. 1 , 2-bis{ jS-Chloropropy Ithio )ethane * 

126. 1 -( /3-Chloroethylthio )-2-butoxye thane* 

127. 1 -( jS-Chloroethylthio )-2-butylthioethane * 

128. l,3-6fs(/3-Chloroethylthio)butane 

129. 1 ,4-bis{ /3-Chloroethylthio )butane * 

130. 2,3-6fs(/3-Chloroethylthio)butane* 

131. If5-bis{ /9-Chloroethylthio )pentane * 

132. l,6-6fs(j8-Chloroethylthio)hexane* 

133. l,5-6fs(j8-Chloropropylthio)pentane* 

134. a, a:-6fs(|8-Chloroethylthio)toluene* 

135. 1 ,8-&fs(/3-Chloroethylthio)octane* 

1 36 . a,a'-bis{ /3-Chloroethylmercapto )-p-xylene 

137. l,9-6fs(/3-Chloroethylthio)nonane* 

138. 1,1 0-bis{ /3-Chloroethylthio )decane * 

139. l,2-Diphenyl-l,2-6fs(i8-chloroethylthio)ethane* 

140. 9,10-6fs(|8-Chloroethylthio)stearic acid* 

141. 6fs(/3-Fluoroethylthiomethyl) sulfide* 

142. 5fs(|8-Chloroethylthiomethyl) sulfide* 

143. <m(/8-Chloroethylthio)methane 

1 44 . /3-( /3-Chloroethylthio )ethy 1-/3 '-( jS-chloroethoxy )- 

ethyl sulfide* 

145. 6fs[/3-(/3-Chloroethylthio)ethyl] ether (T) 

146. 6fs[j8-(/3-Cyanoethylthio)ethyl] ether* 

147. 6is[j8-(j8-Chloroethylthio)ethyl] sulfide* (di H) 

148. 6fs[jS-(/3-Bromoethylthio)ethyl] sulfide* 

149. s[j8-(/3-Thiocyanoethy Ithio )ethyl] ether* 

150. s[/8-(/3-Phenoxyethy Ithio )ethyl] sulfide* 

151. 6fs[j8-(/3-(2,4,6-Tribromophenoxy)ethylthio)- 

ethyl] sulfide* 

152. l,2,3-<m((8-Chloroethylthio) propane* 

153. 6fs[/8-(/3-Chloropropylthio)ethyl] ether* 

154. 6fs[a!-Methyl-/3-(/3-chloroethylthio)ethyl] ether 

155. 5fs[/3-(/3-Chloropropylthio)ethyl] sulfide* 

156. 6fs[/8-(j8-Chloroethylthio)propyl] sulfide* 

157. l,l,l-^m((8-Chloroethylthiomethyl) ethane 

158. 6fs[a-Methyl-/3-(/3-chloropropylthio)ethyl] ether* 

159. 6fs[/3-(j8-Chloropropylthio)propyl] sulfide* 

160. l,2-6fs(/3-(/3-Chloroethylthio)ethylthio) ethane* 

161. 1,1, 2, 2-<e^mA:fs( /3-Chloroethylthio) ethane 

162. fetmA:fs(/3-Chloroethylthiomethyl) methane 

163. 6fs[/3- {/3-(j8-Chloroethylthio)ethylthio) ethyl] 

ether* 

164. 6fs[/3-{/3-(j8-Chloroethylthio)ethoxy} ethyl] sul- 

fide* 

165. 6fs[/3-{/3-(/8-(/3-Chloroethylthio)ethoxy)ethylthio} 

ethyl] ether* 

166. 5fs[/3- {/3-(/3-(/8-(/3-Chloroethylthio)ethoxy )ethyl- 

thio)ethoxyl ethyl] sulfide* 

167. 6is[i8-[/8- {/3-(j8-(/3-(i8-Chloroethylthio)ethoxy)- 

ethy Ithio )ethoxy } et hylthio]ethy 1] ether* 


53 

bpO.003 

65° 

53 

34, 54 


mp 

-15° 

53 


8, 59 




34, 18, 54, 





179 

59 




34, 54 





243c 





243c 

53 

bpO.016 

108° 

53 

34, 54 

59 




34, 54 

59 

mp 

75.5-77° 

59 

56 


bpi^ 

139.5° 

238b 

238b 


bp2“ 

125° 

247 

247 

53 

bpO-003 

35-40° 

53 

34, 54 

See text 

bp2 

174° 

247 

See text 



1.2445 

247 


53 

mp 

73-75° 

53 

34, k 

53 

IjpSxlO’-SxlO--* 

41-42° 

53 

34 

63 

bpO.Ol 

40° 

63 

34, 54 



1.5655 

63 


53 




34 


Not all the British reports concerning compounds marked with an asterisk are available in this country. 


ence 176. 


References are contained in refer- 


SECRET 


TABULATION OF ORGANIC SULFUR COMPOUNDS 


49 


Table 3 {Continued). 





Compound 

Reference 

to 

synthesis 

Physical properties 
Property Reference 

Reference to 
toxicity 
data 

168. /3-Oximinoethyl ethyl sulfide* 






1 69. |8-( /3-Chloroet hylthio )ethy Itrimet hy lammonium 
chloride 





2 

170. p-Aminophenyl-j8-(/8-chloroethylthio)ethylamine 
hydrochloride* 






171 . N-/3-Chloroethylthiomorpholine* 

16 

bpO.5 

77-80° 

16 

34 

172. N-)8-Chloroethylthiomorpholine hydrochloride 

16 

mp 

208-209° 

16 


173. N-/3-Hydroxyethylthiomorpholine hydrochloride 

16 

mp 

160-163° 

16 


174. 6is(j8-Oximinoethyl) sulfide* 






175. 6is[/3-(6ts(/3-Chloroethyl)amino)ethyl] sulfide* 

26 

mp 

24.2-24.7° 

26 

34 



nv-^ 

1.5287 

26 


176. Methyl-6ts(i8-ethylthioethyl)amine 





241f 

177. Methyl-6is(j8-(/3-chloroethyrthio)ethyl)amine 
hydrochloride 

36 

mp 

70-72° 

36 

34 

178. Ethyl-6zs(/3-(i8-chloroethylthio)ethyl)amine hy- 
drochloride 

39 

mp 

62-64° 

39 

34 

179. N,N-6fs(/3-(j8-Chloroethylthio)ethyl)aniline hy- 
drochloride 

36 

mp 

69-71° 

36 

34 

1 80. tris{ |8-( /3-Chloroethylt hio )ethy 1 )amine 

181 

mp 

52° 

181 

181 

181. a-Chloromethylthiophene 

8 

bp^3 

71-76° 

8 


182. co-Chloroacetyl thiophene* 






183. co-Bromoacetylthiophene* 






184. 2-Chloroacetyl-5-nitrothiophene* 






185. Diphenyl-a-thienylstibine* 






186. Phenyldithienylstibine* 






187. 2-Chloromercurithiophene* 

44 

mp 

183-184° 

44 

34 

1 88. 2,5-bis{ Chloromercuri )thiophene* 






189. 2-(p-Aminophenyl)6-methylbenzthiazole* 






190. N-jS-Chloroethylphenothiazine 

61a 





191. Dimethyl trisulfide 

53 

bp2® 

bp^ 

64° 

53 

34 

192. Dimethyl tetrasulfide 

53 

56-69° 

53 

34 




1.6621 

53 





1.3008 

53 


193. 6is(/3-Chloroethyl) disulfide* 

8 

bp^ 

80° 

8 


194. 5zs(Qr-Chloroethyl) trisulfide* 






195. 6is(/3-Chloroethyl) trisulfide* 

35 

mp 

30.5-31.5° 

35 

34, 54 

196. 6ts(/3-Chloroethyl) pentasulfide 

35 

nj)^^ 

1.6753 

35 

34, 54 

197. 6ts(l,3-Dichloroisopropyl) disulfide 





54 

198. 6is(2-Aminophenyl) disulfide 






199. 6ts(a-Chloromethyl) sulfoxide* 






200. Divinyl sulfoxide* 





34, 54 

201. /3-Chloroethyl vinyl sulfoxide 





34, 54 

202. 6fs(i8-Chloroethyl) sulfoxide* 

8 

mp 

108-110° 

8 

34 

203. Thiodiglycol sulfoxide 

65a 

mp 

110° 

65a 

54 

204. 2,5 (or 1,3) Dihydrothiophene sulfoxide 






205. 6ts-Sulfoxide of l,2-6fs(i8-chloroethylthio)ethane 
(2 isomers) 

53 

mp 

148° 

53 

34, 54 

206. 6fs-Sulf oxide of l,2-6fs(/3-hydroxyethylthio)- 
ethane (mixture of isomers) 

65c 

mp 

90-101° 

65c 

34 

207. 6fs(Ethoxyethyl) sulfoxide* 






208. 6fs-Sulfoxide of 6fs(/3-(/3-chloroethylthio)ethyl) 
ether (2 isomers) 

51 

mp 

100-101° 

51 

56 



mp 

106-107° 

51 


209. mono-Sulf oxide of 6fs(/3-(/3-chloroethylthio)ethyl) 
sulfide* 






210. Diphenyl sulfoxide* 






211. 6fs(o:-Chloromethyl) sulfone* 






212. Methyl vinyl sulfone* 






213. Methyl /3-chloroethyl sulfone* 







* Not all the British reports concerning compounds marked with an asterisk are available in this country. References are contained in refer- 
ence 176. 


SECRET 


50 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


Table 3 {Continued). 


Compound 


Reference 

to 

synthesis 


Physical properties 
Property Reference 


Reference to 
toxicity 
data 


214. Divinyl sulfone* 

53 




34, 54 

215. /3-Bromovinyl vinyl sulfone* 


bp22 

137° 

197 

197, 241d 

216. 5ts( /3-Bromovinyl) sulfone* 

217. Ethyl vinyl sulfone* 


mp 

58-59° 

241d 

197, 241d 

218. /3-Chloroethyl vinyl sulfone 

219. /3-Chloroethyl ethyl sulfone* 

53 

bpi7 

152-154° 

53 

34, 54 

220. 5ts(|8-Chloroethyl) sulfone* (H sulfone) 

53 

bp^ 

155° 

53 

34, 54 



mp 

51.5-52.5° 

53 


221. 6ts(/8-Bromoethyl) sulfone* 

222. /8-Chloroethyl-a', jS'-dibromoethyl sulfone* 


mp 

63-64° 

197 

197, 241d 

223. 6is(Dibromoethyl) sulfone (2 isomers) 


mp 

138° 

241d 

197, 241d 



mp 

72-73° 

241d 


224. Thiodiglycol sulfone 

225. 2,5 (or 1,3) Dihydrothiophene sulfone* 

226. 2-Chlorotetrahydrothiophene sulfone* 

227. N-/8-Chloroethylthiazan sulfone* 

228. N-/8-Chloroethylthiazan sulfone hydrochloride* 

229. N-/3-Hydroxyethylthiazan sulfone hydrochloride* 

230. Diallyl sulfone* 

65a 

mp 

.!.... 05 

O 

65a 

34, 54 

231. 6t.s(7-Chloropropyl) sulfone* 

232. Phenyl chloromethyl sulfone* 

233. Phenyl vinyl sulfone* 


mp 

64-65° 

197 

197, 241d 


234. /3-Chloroethyl phenyl sulfone* 

235. /3-Chloroethyl p-nitrophenyl sulfone 

236. /8-Chloroethyl 2,4-dinitrophenyl sulfone 

237. /8-Chloroethyl p-tolyl sulfone* 

238. Diphenyl sulfone* 

239. 6ts(2-Chlorocyclohexyl) sulfone* 




... 

34,’ 54 

240. p-Thioxane sulfone* 

241. 6ts-Sulfone of 5ts(j8-chloroethylthio)methane* 

242. 6ts-Sulfone of l,2-6is(vinylthio)ethane* 

65b 




34 

243. 6ts-Sulfone of l,2-6ts(/3-chloroethylthio)ethane* 

53 

mp 

202-204° 

53 

34 

244. 5ts-Sulfone of l,2-6ts(/3-hydroxyethylthio)ethane 

65c 

mp 

113-115° 

65c 

34 

245. 5ts-Sulfone of l,4-6ts(/3-chloroethylthio)butane* 

246. 5ts-(Methoxyethyl) sulfone* 

247. 6ts(Ethoxyethyl) sulfone* 

248. 6ts-Sulfone of 6ts(i8-(/8-chloroethylthio)ethyl) ether 

249. 5ts(/3-(/3-Chloroethylthio)ethyl) sulfone* 

250. 6ts(/3-Isoamyloxyethyl) sulfone* 

51 

mp 

70-71° 

51 

56 

251. /3-Fluoroethyl thiolacetate 

59 

bpioo 

85-87° 

59 

34 



VOpO 

21.4 

38 


252. /8-Chloroethyl thiolacetate 

253. Diethylthallium thioacetate 

19 

mp 

181-183° 

19 

34, 54 

254. Triethyllead thioacetate* 

241 

mp 

44° 

241 


255. S-/3-Chloroethyl fluorothiolacetate 

55 

bp^” 

80-81° 

55 

34, 238b 

256. Phenyl fluorothiolacetate 

241g 

mp 

36.5-37.5° 

241g 

238a 



bpi* 

132° 

241g 


257. /3-Chloroethyl chlorothiolacetate* 

258. Chloroacetyl thiophenol* 

259. 5ts( Chloroacetyl) sulfide* 

260. /3-Chloroethyl bromothiolacetate* 

261. Methyl y-fluorothiolbutyrate 

33, 55 

bp® 

54° 

33 

34 




1.4587 

33 





1.1135 

33 




voP® 

8.44 

33 


262. Methyl 7-fluoro-/3-hydroxythiolbutyrate 

55 

bp®-2 

68-71° 

55 

34 




1.4872 

55 



* Not all the British reports concerning compounds marked with an asterisk are available in this country. References are contained in refer- 
ence 176. 


SECRET 


TABULATION OF ORGANIC SULFUR COMPOUNDS 


51 


Table 3 {Continued). 


Reference 




Reference to 


to 


Physical properties 

toxicity 

Compound 

synthesis 

Property 

Reference data 

263. 6ts(/3-Chloroethyl) dithioloxalate 

53 

mp 

43° 

53 

34, 54 



bpi 

153-160° 

53 


264. Diethyllead dithioacetate* 

241 

mp 

84.5-85° 

241 


265. /3-Chloroethyl thiolcarbonyl chloride 

266. Reaction product of thiophosgene and jS-chloro- 

64b 

bp 

ca. 150° 

64b 

34 

ethylmercaptan 

53 




34, 54 

267. /3-Fluoroethyl xanthate* 

268. jS-Xanthylethyltrimethyl ammonium iodide* 


mp 

208-210° 

238a 

238a 

269. Methyl N-ethylthiolcarbamate 

44 

bp29 

118° 

44 

34 



bp39 

123° 

44 


, 



1.078 

44 





1.4978 

44 


270. Methyl N-ethylthionocarbamate 

44 

bp26 

109.5-110.5° 

44 

34 



bp37 

119-121.5° 

44 





1.067 

44 




nc's 

1.5150 

44 


271. /3-(Dimethylamino)ethyl N-methylthiocarbamate 






hydrochloride* 





238c 

272. j8-(Dimethylamino)ethyl N-methylthiocarbamate 






methiodide* 





238c 

273. a-Naphthylthiourea 


mp 

198° 

263 

34 

274. Methyl N-ethyldithiocarbamate 

44 

bp^* 

121-122° 

44 

34 



na^-’ 

1.6139 

44 





1.151 

44 


275. Thallous N-methyldithiocarbamate 

19 





276. Thallous N,N-dimethyldithiocarbamate 

277. Thallous N-ethyldithiocarbamate 

278. Thallous N-isopropyldithiocarbamate 

279. Sodium N,N-diethyldithiocarbamate* 

19 

mp 

124-125° 

19 


280. Thallous N,N-diethyldithiocarbamate 

19 

bpOoi-0.02 190° 

19 




mp 

110-111° 

19 


281. Dimethylthallium N,N-diethyldithiocarbamate 

19 

bp^ 

130° 

19 

34 



bp^ 

138° 

19 


282. Sodium N,N-6ts(j8-hydroxyethyl)dithiocarbamate* 

283. Thallous N-butyldithiocarbamate 

19 





284. Thallous N,N-diisopropyldithiocarbamate 

285. Dimethylthallium N,N-diisopropyldithiocarba- 

19 





mate 

19 

bpi 

130° 

19 

34, 54 



bp6.6 

145° 

19 




mp 

150° 

19 


286. Thallous N-cyclohexyldithiocarbamate 

19 





287. Thallous N,N-dibutyldithiocarbamate 

19 

bpOoi-0.02 230-235° 

19 

• •. • 



mp 

75-77° 

19 

. . . 

288. Dimethylthallium N,N-dibutyldithiocarbamate 

19 

bp°® 

147-148° 

19 


289. Thallous N,N-diisobutyldithiocarbamate 

19 

mp 

165-165.5° 

19 


290. Dimethylthallium N,N-diisobutyldithiocarbamate 

19 

bpO.5 

104-105° 

19 

34 



mp 

73-74° 

19 


291. 6ts(/8-Chloroethyl) trithiocarbonate 

53 

bp2 

85° 

53 

34 




1.5505 

53 


292. jS-Chloroethyldimethylsulfonium chloride 

23 

mp 

147-148° 

23 

34 

293. /3-Hydroxyethyldimethylsulfonium chloride 

23 





294. Methyl-6ts(/3-hydroxyethyl) sulfonium chloride 

23 





295. Methyl-6ts-2-hydroxyethyl sulfonium iodide 

23 





296. Dithiane monomethiodide 

61g 

mp 

168° 

61g 

34 

297. <m(j8-Chloroethyl) sulfonium chloride 

46 



34 

298. S,S-endo-Ethylenedithiane sulfonium dichloride 

46 





299. S-Vinyldithiane sulfonium chloride 

46 






* Not all the British reports concerning compounds marked with an asterisk are available in this country. References are contained in refer- 
ence 176. 


SECRET 


52 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


Table 3 {Continued). 


Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference data 

300. S-/3-Chloroethyldithiane sulfonium chloride 

46 

mp 

144° 

46 

34 

301. S-/3-Hydroxyethyldithiane sulfonium chloride 


mp 

176° 

197, 241d 

197, 241d 

302. Sulfonium salt of thiodiglycol and bis{l3-ch\oro- 
ethyl) sulfoxide 





34 

303. Sulfonium salt of thiodiglycol 6ts(j3-chloroethyl) 

' sulfone 





34, 54 

304. Sulfonium compound of 5fs(2-chloroethyl) sulfide 
and 2 moles of thiodiglycol 

8 

mp 

102-103° 

8 

34 

305. Triethyllead cyclohexylsulfinate 

20 

mp 

132-134° 

20 


306. Triethyllead p-toluenesulfinate 

20 

mp 

86-88° 

20 


307. Methanesulphonyl fluoride* 






308. Methanesulphonyl chloride* 






309. Chloromethanesulphonyl chloride 






310. Trichloromethanesulfonyl chloride* 

11 



. . . 

241e 

311. Ethanesulfonyl chloride 

11 

bp2o 

73.5-75° 

11 

34 

312. 2-Fluoroethanesulphonyl chloride* 



1.370 

11 


313. jS-Chloroethylsulphonyl chloride* 






314. /3-Bromoethanesulfonyl fluoride 

64d 

cr 

o 

90° 

64d 


315. Chloropropanesulfonyl chloride 

Commercial 




34 

316. Butanesulfonyl fluoride 

64c 

bp* 

54-56° 

64c 

34 

317. Butanesulfonyl chloride 

64c 

bp^ 

76-78° 

64c 

34 

318. Ammonium 2-chloroethanesulfonate 





34 

319. Sodium 7-fluoro-/3-hydroxy propanesulfonate 

55 




56 

320. Cadmium m-nitrobenzenesulfonate 

9 





321. Lead m-nitrobenzenesulfonate 

3 





322. Cadmium 2,4-dinitrobenzenesulfonate 

9 





323. Lead 2,4-dinitrobenzenesulfonate 

3 





324. Triethyllead o-toluenesulfonate* 






325. Tripropyllead o-toluenesulfonate 

241 

mp 

87° 

241 


326. Trimethyllead p-toluenesulfonate* 






327. Triethyllead p-toluenesulfonate* 






328. Tripropyllead p-toluenesulfonate 

241 

mp 

73-74.5° 

241 


329. Tributyllead p-toluenesulfonate 

241 

mp 

81-82° 

241 


330. Triethyllead 2-amino-5-toluenesulfonate 

20 

mp 

210° 

20 


331. Triethyllead naphthalene-2-sulfonate* 






332. Tributyllead naphthalene-2-sulfonate* 

241 

mp 

68° 

241 


333. Triethyllead l-amino-4-naphthalenesulfonate 

20 

mp 

238-240° 

20 


334. Dipropylthallium d-camphor-lO-sulfonate 

19 





335. Triethyllead d-camphor-lO-sulfonate 

20 

mp 

172° 

20 


336. Triethyllead p-tolylthiosulfonate 

20 

mp 

109° 

20 


337. 6fs-Triethyllead methanedisulfonate 

241b 




241b 

338. Triethyllead methanesulfonamide* 

241b 

mp 

97° 

241b 

241b 

339. Tripropyllead methanesulfonamide* 

241b 

mp 

67° 

241b 

241b 

340. Triethyllead methanesulfonanilide* 

241b 

mp 

115.5° 

241b 

241b 

341. bf.s-Triethyllead methanedisulfonanilide 

241b 




241b 

342. Triethyllead ethenesulfonanilide 

241b 

mp 

110° 

241b 

241b 

343. Triphenyltin benzenesulfonamide 

241b 

mp 

119° 

241b 

241b 

344. Triethyllead benzenesulfonamide 




. . . 

241c 

345. Tripropyllead benzenesulfonamide 





241c 

346. Triethyllead p-aminobenzenesulfonamide* 

20, 241b 

mp 

173-174° 

20 

241b 

347. Tripropyllead p-aminobenzenesulfonamide 

241b 

mp 

101° 

241b 

241b 

348. Triethyllead o-toluenesulfonamide* 

241b 

mp 

133° 

241b 

• . . 

349. Triethyllead p-toluenesulfonamide* 





241c 

350. Triethyllead p-toluenesulfonanilide* 

241b 

mp 

134° 

241b 


351. Tripropyllead p-toluenesulfonanilide 

241b 

mp 

104° 

241b 

241c 

352. Triethyllead p-toluenesulfon-p-chloranilide 

241b 

mp 

111.5° 

241b 

241b 

353. Triethyllead p-tohienesulfon-p-bromanilide 

241b 

mp 

117° 

241b 

241b 

354. Tripropyllead p-toluenesulfon-p-chloranilide* 

241b 

mp 

123° 

241b 

241b 

355. Triethyllead o-carboxybenzenesulfonimide 

241b 

mp 

135° 

241b 


356. Tripropyllead o-carboxybenzenesulfonimide 

241b 

mp 

130° 

241b 

241b 


* Not al! the British reports eoncerning compounds marked with an asterisk are available in this country. References are contained in refer- 
ence 176. ^ 


SECRET 


TOXICOLOGY 


53 


The high freezing point of H is a disadvantage in 
some instances. For aircraft spray tanks, in particu- 
lar, there was interest in a vesicant mixture which 
would withstand high-altitude temperatures of —30 
to — 40C for several hours without freezing. This 
degree of lowering of the freezing point could be 
attained only by the use of a relatively large per- 
centage of an inert diluent such as acetone or ben- 
zene. Such mixtures suffered from the relatively low 
pay load of active vesicant agent. The freezing point 
could be lowered a small amount by mixture with 
Q or T. The freezing points of eutectic mixtures of H 
with pure Q or T are as follows: HQ (68/32) 4.5 C 
and HT (35/65) approximately —8 

The principal U. S. standard charging was H 
(Levinstein), which with its 30 per cent nonvolatile 
impurities melted at about 8 C. The standard British 
chargings included HT (60/40) melting at about 
0 C and solutions of H containing 10-20 per cent 
benzene. 

The viscosity of H is an important property not 
included in the above tabulation. The size of drops 
of H from spray munitions is a function of the re- 
sistance of the charging to shattering forces upon 
emission and this property is related to the viscosity 
of the material. The addition of “thickening” agents, 
such as methacrylate polymers, was first studied 
from the standpoint of the use of H in high-altitude 
aircraft spray, where large drops were essential to 
prevent a high percentage of evaporation before the 
charging reached the ground. Also, the toxicological 
data showed that large drops of H are more efficient 
than small ones in producing vesication by direct 
contact, particularly against personnel in permeable 
protective clothing. Since high- altitude spray was 
not adopted as a practical procedure, partly because 
of the inherent inaccuracies in aiming, and since the 
primary interest in H became based on vapor effects 
rather than liquid contact, thickened chargings were 
not adopted for standard U. S. munitions. The meth- 
ods for their preparation, however, were carefully 
worked out and field trials performed. The NDRC 
research on the preparation and physical properties 
of thickened H chargings was carried out by Di- 
vision 11. 

5 . 4.2 Detection and Analysis 

Chemical methods for the detection and analysis 
of H are outlined in Chapter 34. The introduction of 
4- (p-nitrobenzyl) pyridine (DB-3) as a colorimetric 


agent for /3-chloroethylthio compounds greatly sim- 
plified the detection problem. The development of 
continuous recording titrimeters for the measure- 
ment of H concentrations led to the wide use of these 
instruments in U. S. and British field trials and as 
integral parts of gassing chambers for toxicological 
measurements. 

H is detectable by odor at about 0.0006 mg/l.^^^ 
Field experience showed that a sulfide odor from 
Levinstein H residues can persist after the active H 
has evaporated. The instructions for troops required 
the wearing of masks whenever H could be detected 
by odor, unless subsequent careful gas reconnaissance 
with DB-3 tubes established the fact that the odor 
was from nontoxic residues, the DB-3 test being 
specific for the active agent. 

The researches on protective clothing, protective 
ointments, and decontamination procedures for H 
and related vesicants are covered in Part IV. 

5.5 TOXICOLOGY 

5 . 5.1 Vesicancy Tests 

The action of the vesicant agents on the skin is 
their most important toxicological property. Since 
World War I extensive data have been accumulated 
on liquid agents tested by application of droplets to 
the bare skin of the forearm. Since the vesicant 
agents can be adequately assessed only against hu- 
man skin, the availability of volunteers has been of 
major importance in this program. 

The performance of skin tests under conditions 
which permit quantitative interpretation of the re- 
sults requires that the testing procedure be carefully 
controlled. The introduction of specially designed 
micropipets (see Chapter 16) has facilitated the 
routine application of very small volumes (0.01 mm^ 
or less).'^’®'^’®'^ Evaporation is a variable entering 
into tests with volatile agents. The term “absolute” 
vesicancy has been introduced by British investi- 
gators to indicate the activity of the compound when 
it is applied to the skin and then covered to prevent 
evaporation. For example, in the usual “open” vesi- 
cation test, Q is many times more potent than H. 
Under conditions of “absolute” or “closed” vesica- 
tion, which is important in the study of the intrinsic 
activity of different molecular structures, the two 
agents are much nearer to each other in activity. 

For the study of the vesicancy of the vapor of an 
agent, rather than that of the liquid in contact with 


SECRET 


54 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


Table 4. Relative vesicancies of H, Q, and T. 


Compound 

Uncovered 

Reference 

Vesicancy relative to H 
Covered Reference 

Vapor 

Reference 

H 

1 


1 


1 


Q 

5* 

199 

2 

199 



T 

3* 

199 

<1 

198 



Methyl-/3-chloroethyl sulfide 



0.06 

199 

<0.1 

30 

Ethyl-jS-chloroethyl sulfide 



0.06 

202 

<0.1 

30 


* More recently determined and higher relative potencies based on median vesicating doses of 32 mg for H, 4 for T, and 0.3 for Q (dissolved 
in dioxane) are given elsewhere.®^ (See Chapter 23.) 


the skin, several techniques have been developed. 
The effect of the vapor on animals in body exposure 
experiments, as outlined in the section on L(C 0 50 ’s, 
gives evidence that bears on the problem. The most 
direct and important of the experimental procedures 
is the use of chambers for the exposure of volunteers 
under conditions of temperature and humidity ap- 
proximating as closely as possible field conditions of 
exposure (see also Chapter 23). For laboratory 
screening of agents on human skin, however, vapor 
cups or other mechanisms for producing burns on 
small areas of the skin of the forearm have been em- 
ployed. In dynamic tests, in contrast to static tests, 
a stream of a known concentration of the gas in air 
may be directed at a small area of skin for a given 
time.^®’®'‘ 

The relative vesicancies of H, Q, and T are listed 
in Table 4. The references to the vesicancy tests on 
the wide variety of sulfur mustard compounds are 
included in Table 3. British surveys of the relation- 
ship of structure and vesicancy are included in the 
Bibliography.^^®’i®*-^®^’202.236 Vesicancy data are sum- 
marized and tabulated by NDRC 17 , 34 , 48 , 52 , 54,68 
also Chapter 23) . 

The data on two of the more volatile analogs of H 
are included in Table 4 for comparison. There would 
be interest in a compound as vesicant as H but more 
volatile. The vesicant potency of H is not ap- 
proached, however, by any of the more volatile 
/3-chloroethylthio compounds. Only among the com- 
pounds with relative low vapor pressure have more 
potent analogs been found. These have the advan- 
tage of greater effectiveness in contact with the bare 
skin but they have poorer penetration through cloth- 
ing and negligible vapor action. 

The laboratory tests give indications of the relative 
activities of the different compounds. The actual 
Ct’s or liquid contaminations required under field 


conditions to incapacitate troops are determinable 
only through chamber and field trials (see Sec- 
tion 5.6). 

5.5.2 L(Cf ) 5 o’s of H, Q, and T 

The L{Ct)^Q values for total exposure of different 
species are summarized in Table 5. 

For agents in this class the L{Ct)Bo for the mouse 
or the rat serves as a useful index of the potency of 
agent even though final assessment may rest on vesi- 
cant action. H has an L{Ct) 5 o for the mouse or the 
rat of about 1,000 mg min/m^ and this figure became 
an informal base line in the screening of new agents. 
Potential persistent agents showing an L{Ct)^o near 
to or less than 1,000 were usually selected for more 
detailed study. In the case of H, it will be noted that 
the species variation is small. The rate of detoxifica- 
tion of H is known to be low in tests on human 
skin and eyes 60k,i69,is7 most of the L{Ct)ho 

experiments, although the data in the case of the 
mouse show an increase in L{Ct)^Q with time which 
is not in line with this generalization. From the data 
on rats the calculated detoxification constant is 
0.002 mg/1.*^ The high toxicity of Q under laboratory 
conditions is a value which could be attained in the 
field only if equally efficient means for production of 
the aerosol could be achieved. The laboratory results 
vary with the particle size obtained in the aerosol 
(see Chapters 12 and 15). 

Among the volatile analogs of H, none of them 
exceed H in toxicity. 6zs(/3-Bromoethyl) sulfide has 
about the same L(C 0 50 for the mouse as does 
The methyl, ethyl, and benzyl-/3-chloroethyl sul- 
fides, for example, are much less active. A summary 
of the relative toxicities of the analogs of H is given 
elsewhere. 

The L(C05 o’s tabulated in Table 5 are a function 
of the action of the vesicant agent on and through 


SECRET 


TOXICOLOGY 


55 


Table 5. L(Ct) 5 oS of H, Q, and T for different species. 
(Exposure of the pntire animal* — 15-day observation period.) 


Agent 

Species 

Exposure 

times 

(min) 

L{Ct),o 

(mg min/nP) 
or suggested value 
where number of 
animals is 
small 

A = anal. cone. 

N = nom. cone. 

Number 

of 

animals 

used 

Reference 

H 

Mouse 

2 

860 

A 

160 

80 



10 

1,200 

A 

230 

50 



10 

1,200 

A 

180 

123 



60 

f,380 

A 

140 

80 



360 

4,140 

A 

277 

80 


Rat 

2 

840 

A 

50 

80 



10 

800 

N 

48 

50 



10 

850 

A 

80 

80 



60 

900 

A 

60 

80 



360 

1,512 

A 

40 

80 


Guinea pig 

10 

1,700 

N 

19 

50 


Rabbit 

10 

900 

N 

8 

50 



ca. 30 

1,025 

A 

80 

83b 


Cat 

10 

700 

N 

10 

50 


Dog 

10 

600 

N 

8 

50 


Goat 

10 

1,900 

A 

60 

166 


Monkey 

10 

800 

N 

3 

50 

Q 

Mouse 

10 

170 

A 

190 

50 



10 

350 

A 


120 



10 

270 

A 

200 

82 


Rat 

10 

400 

N 

34 

50 


Guinea pig 

10 

>1,600 

A 

26 

50 


Rabbit 

10 

2,000 

N 

12 

50 


Cat 

10 

900 

N 

11 

50 


Dog 

10 

1,400 

N 

6 

50 

T 

Mouse 

10 

l,650t 

A 

180 

18 

HQ 90/10 

Mouse 

10 

820 

A 

200 

120 

HQ 75/25 

Mouse 

10 

770 

A 

240 

120 

HT 60/40 

Mouse 

10 

820 

A 

260 

123 

*The toxicides 

in this table are 

for total exposure of the animals at low rates of air flow. (See Table 6.) 



t The aerosol was generated under conditions different from those prevailing in 

the preceding tests. Under the conditions of this 

experiment, 


Q gave an L{Ct)io of 700. 


the skin of the animal as well as on the lungs. Toxi- 
cological techniques have been worked out in de- 
tail for differentiating the relative contributions of 
the actions of the agent on the lungs and on the body 
surface. In the case of agents such as T or Q, which 
were dispersed by atomization into the exposure 
chambers, the rate of air flow was an additional vari- 
able which affected the L{Ct) 5 o by influencing the 
impingement of the aerosol particles on the skin. 
The most extensive studies have been made with the 
mouse. The results with HNl, HNS, and L are in- 
cluded for comparison in Table 6. 

The body exposure experiments were carried out 
in an apparatus which exposed the body of the ani- 
mal to the toxic agent while the head was in uncon- 
taminated air. In the inhalation experiments only 
the head was exposed to the toxic atmosphere. The 
linear velocity of air flow through the chamber was 


Table 6. Effects of flow rate and type of exposure on 
L{Ct)r^oS of vesicant agents for mice.* 


Type of 

Degree of 






exposure 

air flow 

H 

Q 

HNl 

HN3 

L 

Total 

Low 

1,200 

170 

900 

590 

1,400 

High 

1,400 

100 

900 

300 

900 

Body 

Low 

3,500 

1,500 

4,800 

1,000 

1,900 

High 

3,400 

510 

3,100 

370 

1,200 

Inhalation 

Low 

1,600 

280 

1,300 

1,100 

1,400 

High 

1,600 

250 

1,300 

1,200 

1,500 


* Exposure periods are 10 minutes except for some body exposures 
to HNl and Q ranging from 5 to 45 minutes. 


6 niph at the low flow rate and 3 mph at the high 
flow rate. 

With H, which is present entirely in the vapor 
form, the L{Ct)^o for the three types of exposure is 


SECRET 


56 


MUSTARD GAS AND OTHER SULFUR MUSTARDS 


not significantly altered by change in flow rate. It 
might be anticipated that an increase in wind speed 
would tend to disturb the cushion of air held in the 
fur of an animal and increase the concentration of 
vapor at the surface of the skin. The experiments 
with HNl give an indication of such an effect but 
those with H give none. In no case is the inhalation 
toxicity significantly affected by flow rate. 

With Q, which is present as an aerosol, the body 
toxicity increased markedly with increase in air flow. 
This is also true of HNS, which is present in part as 
an aerosol, and of L (see Chapter 7). (The authors of 
Table 2 point out that the same toxicity for L by 
total exposure and by inhalation at low flow is an 
anomaly not in line with the rest of the data.) 

For H, HNl, and HNS, the reciprocal of the 
L{Ct)^Q by total exposure corresponds fairly closely 
to the sum of the reciprocals of the L (Case’s by body 
exposure and by inhalation, respectively.^® 

The body toxicities become less significant relative 
to the inhalation toxicities as the size of the animal 
increases. For the dog and the monkey the body 
L(C05 o’s are about 11,000 and 14,000 respectively.^ 

It is reasonable to assume that the L(C05o of H 
for man by exposure which includes inhalation falls 
within the range of values in Table 5, namely, 1,000 
to 2,000 mg min/m^. In calculations on the effective- 
ness of H against troops, however, in view of the ade- 
quacy of the modern gas mask, this value has logi- 
cally received less consideration than those based on 
the production of casualties by body exposure. The 
power of H lies primarily in its ability to produce 
casualties despite the mask. In the case of man, the 
evidence indicates that the actual production of 
death by body exposure requires C^’s of more than 
10,000 in temperate weather. There are no data to 
establish with certainty whether the L{Ct ) of H 
for man by body exposure fall within the range that 
can be attained by feasible munition expenditures. 
But death is not the objective which requires primary 
consideration in the assessment of H. Sublethal skin 
injuries from H are capable of totally disabling 
troops for periods of weeks and, as outlined in Sec- 
tion 5.6, sufficient data are available from tests on 
man to indicate the dosages required to yield differ- 
ent degrees of disability. Since man is a sweating 
animal and the effectiveness of H on skin is markedly 
affected by the degree of surface moisture (see Chap- 
ter 23), the results on body exposure of animals to 
H have no direct bearing on the estimation of casu- 
alty-producing dosages for man. The experiments on 


body exposure have had a direct use in supplying 
animals for study of the systemic effects from ab- 
sorbed H under conditions where the lungs are 
protected. 

5.5.3 Action of H on the Eyes 

The toxicity of H vapor to the eyes is a subject of 
special importance. Serious injury may be produced 
by low dosages, and loss or impairment of vision is a 
casualty effect of primary significance. In addition 
to the L(C0 50 tests, the principal vesicant gases were 
screened for effectiveness against animal eyes.®®*^ ® 
In the dog corneal ulceration is produced by H at 
Cfs, of about 400 mg/l.®®‘^ In the rabbit severe corneal 
opacity is produced at Ct 800 with clearly char- 
acterized ocular lesions of graded se^^erity over the 
range from Ct 200 to Ct 1,200.®^-^®^ This gradation 
was utilized by the Bushnell, Florida, installation as 
a practical bioassay for determining Ct values of H 
in field trials. 

The animal tests on eyes have proved useful for 
preliminary tests on toxicity but tests on man have 
been essential for the establishment of casualty- 
producing dosages. British investigators have shown 
by chamber tests that the human eye is about four 
times as sensitive to H as the rabbit eye.^®^ A Ct of 
100 will cause serious impairment of vision for 24- 
48 hours and it is estimated that a Ct of 200 will pro- 
duce temporary blindness for a week or more. 

Liquid H and T and particles of the solid vesicants 
in the eye all produce extremely severe ocular lesions. 
The subject of the action of vesicants on the eye has 
been reviewed in detail by the Committee on Medi- 
cal Research [CMR].®® A wide variety of organic com- 
pounds was supplied by NDRC Division 9 for the 
studies of possible therapeutic agents for liquid 
vesicants in the eye. 

The pathology and the physiological mechanism 
of action of vesicants are treated in Part III of this 
report. The data reviewed there together with the 
sections on these subjects in the reference just cited ®® 
give the basis for the conclusion that prompt decon- 
tamination is the only treatment of special value in 
mustard burns of the skin or of the eye. 

5.5.4 Toxicity in Drinking Water 

In connection with the program on decontamina- 
tion of water supplies (Chapter 39) it has been neces- 
sary to determine the toxicities of compounds which 
might be produced by hydrolysis or in the course of 
chemical treatment. Methods based on oxidizing 


SECRET 


EVALUATION AS WAR GASES 


57 



Table 7. Toxicity 

in drinking water. 






Cone, in 

Duration of 






water 

administration 

Results on mice 




(ppm) 

(days) 

Deaths 

Weight gain 

Reference 

H-sulf oxide 


100 

30 

0/30 

Normal 

60b 

H-sulfone 


100 

30 

0/30 

Normal 

60b 

Sulfonium salt of H and 2 moles of thiodiglycol 

100 

4 

13/30 


60b 





(in 30 days) 





100 

4 

6/30 


60d 



100 

30 

6/30 


60d 



50 

30 

0/30 

Normal 

60c 



25 

30 

0/30 

Normal 

60c 

Sulfoxide of the above sulfonium salt 


1,000 

30 

15/30 


60b 



100 

30 

0/30 

Normal 

60b 

Sulfilimine of H and chloramine-T 


Sat. sol. 







<100 

30 

2/30 

Normal 

60b 

Thiodiglycol sulfoxide 


1,000 

28 

1/30 


60a 

Thiodiglycol sulfone 


1,000 

28 

0/30 


60a 

Q-sulf oxide 


100 

7 

0/20 


60e 





1/20 


60e 


agents would yield sulfoxides and sulfones. Repre- 
sentative data on the toxicities in drinking water of 
derivatives of H are given in Table 7. 

For H and related )3-chloroethyl vesicants the 
maximum safe concentration is considered to be 
2 ppm, as indicated by the DB-3 test, for water to be 
used for a period not greater than 1 week.^* In the 
tests on mice the sulfoxides and sulfones in this series 
are shown to be relatively nontoxic. The sulfonium 
salt of H and thiodiglycol, however, retains consider- 
able toxicity. It reacts with DB-3 and this color test 
thus serves to indicate active sulfonium salts present 
as well as unchanged H. 

LDso doses of sulfur mustards by intravenous, sub- 
cutaneous, or percutaneous routes of administration 
are tabulated in Chapter 22. 

5.6 EVALUATION AS WAR GASES 

Among the more volatile vesicant agents H retains 
its position as the most effective war gas in this class. 
For special purposes the nitrogen mustards would 
have some uses (see Chapter 6) but, among the hun- 
dreds of analogous compounds that have been stud- 
ied since H was first used in 1917, no agent has been 
found to have a more advantageous combination of 
toxicological, chemical, and physical properties. 

There would have been interest in an agent as 
vesicant as H vapor but much more volatile. In the 
absence of an agent meeting these specifications, two 
approaches were made to the problem of increasing 
the rate of evaporation of H in the field. At the close 
of World War II, these two approaches had not 


reached a stage of completion permitting final assess- 
ment of their potential usefulness. The first was the 
thermal generator bomb under development by Di- 
vision 10 NDRC. The second approach was the addi- 
tion of several per cent of a pyrogenic material, such 
as white phosphorus, to the H charging, an inter- 
esting modification developed by Division 11 
NDRC.«« 

The British, Canadian, Australian, and United 
States field test installations greatly extended the 
technical knowledge of the field behavior of H over 
the status of the information at the close of World 
War I. Division 9 NDRC was a participating agency 
throughout the studies on H munitions at the Chem- 
ical Warfare Service Mobile Field Unit operating at 
Bushnell, Florida, during 1944 and 1945. The results 
of this extensive program, which was one of the most 
important phases of chemical warfare research, have 
been thoroughly summarized in the formal reports 
from Dugway Proving Ground and elsewhere. 

The chamber trials on H carried out on human 
volunteers in conjunction with the research pro- 
grams of the field installations have provided docu- 
mentation for the estimation of the casualty-produc- 
ing power of H vapor on man. Table 8 summarizes 
the quantitative information on the amounts of H 
vapor required to produce physiological effects of 
military significance. 

The nonvolatile vesicants Q and T, in mixture with 
H, possess the advantage of providing a contamina- 
tion of ground and materiel which would remain a 
potential contact hazard (but not a vapor hazard) 
for days under meteorological conditions where H 


SECRET 


58 MUSTARD GAS AND OTHER SULFUR MUSTARDS 



Table 8. 

Dosages of H vapor for production of injuries in man.^'^^ 



Protection 

Effect 

H 

Hot and humid 
weather, temp, 
above 80 F, 
sweating skin 

dosage (mg min/m®) 

Warm weather, 

temp. 60-80 F, Cool weather, 
skin not wet temp. 40-60 F, 

with sweat cool, dry skin 

Disability 

Time of 
onset 

Duration 

None 

(No mask or 
protective 

No significant 

injury; maximum 
safe dosage 

50 

50 

50 




clothing) 

Eye damage of 
threshold military 
significance 

100 

100 

100 

Partial 

6-24 hr 

1-3 days 


Temporary 

blindness 

200 

200 

200 

Total 

3-12 hr 

2-7 days 

Mask 

(No protective 
clothing) 

No significant 

injury; maximum 
safe dosage 

100 

150 

400 




Skin burns of 

threshold military 
significance 

200 

300 

1,000 

Partial 

2-12 days 

1-2 weeks 


Severe genital 
burns 

500 

1,000 

2,000-4,000 

Partial 

2-7 days 

1-4 weeks 


Severe generalized 
burns 

750 

2,000-4,000 

4,000-10,000 

Total 

About 

24 hr 

1-2 weeks 






(Partial) 

(4-12 hr) 

(3-6 weeks) 


would persist for a number of hours. In contact with 
the bare skin, Q is the most powerful vesicant known. 
The disadvantages of mixing Q with H relate chiefly 


to the use against a target which it is desired to oc- 
cupy quickly, since the presence of Q would present 
a persistent hazard to the occupying troops.^® 


) 


SECRET 


Chapter 6 

NITROGEN MUSTARDS^ 

By Arthur C. Cope, Marshall Gates, and Birdsey Renshaw 


6.1 INTRODUCTION 

D uring the 1930’s the synthesis of various ter- 
tiary 6is(i8-chloroethyl)amines, now called nitro- 
gen mustards, was described in the open literature 
and references made to their vesicant actions. As a 
consequence, these substances were investigated 
by the chemical warfare services of most or all na- 
tions before and during World War II. The nitrogen 
mustards that were found to merit the most seri- 
ous consideration were ethyl-6fs (/3-chloroe thy 1) amine 
(HNl), methyl-6fs(i8-chloroethyl) amine (HN2), 
(/8-chloroe thy 1) amine (HNS), and isopropyl- 
(|8-chloroe thy 1) amine. The toxicity, vesicancy, 
eye-injurant action, potential effectiveness as water 
poisons, relative lack of odor, order of volatility, and 
low freezing point of these compounds made them 
potential competitors of the standard persistent 
agent, mustard gas, 52s(jS-chloroethyl) sulfide (H). 

HN2 is not now seriously considered for use as a 
war gas because of the degree of instability it has 
been found to possess, and isopropyl-6fs(i(3-chloro- 
ethyl)amine is disqualified because its toxicological 
potencies are somewhat inferior to those of HNl 
and HNS. 

HNl and HNS remain as potential substitute 
agents for H. Although they are not believed to pos- 
sess the general utility of H, they may be of value 
under special circumstances. In particular, HNS 
would seem to be admirably suited for use in high 
explosive-chemical shell, and it was the intention of 
the German Army to use it in this way in the event 
of chemical warfare. In so far as classical chemical 
warfare continues to be of military importance, the 
present reviewers believe that this method of em- 
ploying HNS merits careful consideration from both 
the offensive and defensive points of view. 

This chapter is not in itself a complete review of 
all available information relating to the value of the 
nitrogen mustards as chemical warfare agents. It 
should be read as a supplement to the several 
previous assessrnents that are already avail- 


® Based on information available to Division 9 of the Na- 
tional Defense Research Committee [NDRC] as of March 1, 


1946. 


No attempt is made to dupli- 
cate the chemical and physiological phases of the 
subject that are covered in detail in Chapters 19 
to 2S. 


6.2 SYNTHESIS AND PROPERTIES 


6.2.1 Synthesis 

Many nitrogen mustards and related compounds 
were prepared during World War II for evaluation 
as possible chemical warfare agents (see Table 1). 
The following four tertiary 6fs(j(3-chloroethyl)amines 
proved to have the greatest practical importance and 
were studied most intensively. 


CH 2 CH 2 CI 

/ 

CHa— N 

\ 

CH 2 CH 2 CI 
Methyl-6fs(j3-chloro- 
ethyl)amine (HN2) 


CH 2 CH 2 CI 

/ 

CH3CH2— N 

A 

CH2CH2C1 

Ethyl-5fs(/3-chloroethyl)- 
amine (HNl) 


CH 2 CH 2 CI 


CH 2 CH 2 CI 


/ / 

N— CH 2 CH 2 CI (CH 3 ) 2 CH— N 

\ \ 


CH 2 CH 2 CI 

<rfs(|8-Chloroethyl )- 
amine (HNS) 


CH 2 CH 2 CI 
Isopropy l-6f s( |8-chloro- 
ethyl)amine 


The most practical method for preparing all com- 
pounds of this class is from the corresponding 
hydroxy compounds (ethanolamines) and thionyl 
chloride, e.g., 

N(CH2CH20H)3 + SSOCI 2 

N(CH2CH2C1)3-HC1 + SSO 2 + 2HC1 


The free amines or their hydrochlorides may be used 
in the reaction, which is conducted either in a solvent 
such as ethylene chloride or without a solvent. The 
resulting hydrochloride salts are converted to the 
free bases with aqueous sodium hydroxide. This 
method for preparing HNS is described in the open 
literature.^®^’^®^’^®^'^®^ Similar preparations of HN2 
are also described. 

The application of the method to the preparation 
of the large series of homologs listed in Table 1 is dis- 
cussed elsewhere 2, 4, 5, 7, 9, 10,11. 16,23, 32, 83, 120,136, 157,158,163, 179a 


SECRET 


59 


60 


NITROGEN MUSTARDS 


Table 1. Nitrogen mustards and related compounds examined as candidate chemical warfare agents. 

The compounds are arranged in four large classes: (1) derivatives of primary amines, (2) derivatives of secondary 
amines, (3) derivatives of tertiary amines, and (4) quaternary ammonium salts. Within the first two, the arrangement is 
in order of increasing number of carbon atoms attached to nitrogen, with acyl and other derivatives listed under the parent 
amines. In the last two, the arrangement is in order of increasing number of carbon atoms attached to nitrogen. Hetero- 
cyclic compounds are not segregated. 

The following abbreviations are used: noS refractive index at t C; d*, density in g/ml at t C; specific gravity at 
ti C in reference to water at t 2 C; mp, melting point in C; bp^, boiling point in C at p mm Hg; vpb vapor pressure in 
mm Hg at < C; and voh, saturation concentration (volatility) in mg/1 at t C. 

British reports describing the examination of compounds marked with an asterisk are not all available. 

Centigrade scale is used throughout the table. 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Reference to 
toxicity 
and 

vesicancy 

data 

A. Derivatives of 'primary amines 






1. 

/3-Chloroethylamine 

11 

bpO.5 

10-20° 

11 


2. 

jS-Chloroethylformamide 

7 

bpO.3 

93-96° 

7 


3. 

j8-Chloroethyl-N-nitrosoformamide 

7 

bpO.8 

78-80° 

7 


4. 

N-jS-Chloroethylacetamide 

7 

bp2-3 

107-111° 

7 


5. 

N-/3-Chloroethyl-N-nitrosoacetamide 

7 

bpO.5 

70-72° 

7 

29, 41 

6. 

N-j8-Chloroethylfluoroacetamide 

60c, 178 

bpO.3 

77° 

178 

29 




mp 

65° 

178 


7. 

N-/3-Chloroethylchloroacetamide* 

7 

mp 

54° 

7 


8. 

N-/3-Chloroethyltrichloroacetamide 

7 

mp 

75° 

7 


9. 

Ethyl N-/3-chloroethyloxamate 

7 

mp 

68° 

7 


10. 

Methyl N -jS-chloroethylcarbamate 

7 


1.4575 

61 

29, 134 




bp^'* 

100° 

7 


11. 

Methyl N-/3-chloroethyl-N-nitrosocarbamate 

7, 116, 124, 


1.4666 

116 

29, 41, 116, 



162, 55 




124 





1.2053 

116 





bpO.5 

72-76° 

7 

. . • 




vopo 

0.600 

31 

• 

12. 

Methyl N-/3-chloroethyl-N-nitrocarbamate 

7 

bpO.3 

95-100° 

7 

29, 41 




VOpf 

0.138 

31 


13. 

Ethyl N-/3-chloroethylcarbamate 

7 

bp^** 

100° 

7 


14. 

Ethyl N-/3-chloroethyl-N-nitrosocarbamate 

7 

bpi4 

92-93° 

7 

29, 41 




voP“ 

0.426 

31 


15. 

/3-Fluoroethyl N -/3-chloroethylcarbamate 

53a 

bp“-^ 

105-108° 

53a 


16. 

j3-Fluoroethyl N-j8-chloroethyl-N-nitrosocarba- 







mate 

53a 

bp2 

118-121° 

53a 

29 

17. 

/3-Chloroethyl N-/3-chloroethyl-N-nitrosocarba- 







mate 

7 

bp^ 

120° 

7 


18. 

Isopropyl N-/8-chloroethyl-N-nitrosocarbamate 

7 

bpO.6 

80° 

7 

29, 41 

19. 

Butyl N-j8-chloroethyl-N-nitrosocarbamate 

7 

bpO.6 

95° 

7 

29, 41 

20. 

s( jS-Chloroethy 1 ) urea 

7 

mp 

125° 

7 


21. 

N -/3-Chloroethy laminophosphory 1 chloride 

53g 

bp^ 

146° 

53g 

29 

22. 

Sodium salt of N-nitro-/3-chloroethylamine 

50 





23. 

/3-Chloroethylisocyanate 

53c 

bp 

135-137° 

60b 

29 

24. 

/3-Chloroethylisothiocyanate 

11 

mp 

104° 

11 


25. 

/3-Chloroethyl azide 

21 


1.4658 

21 

29 




bp22.5 

38-38.5° 

21 


26. 

/3-Bromoethyl azide 

21 


1.5082 

21 





bp22 

51-52° 

21 


27. 

/3-Idoethyl azide 

21 

bp2o 

67-69° 

21 


28. 

/3-Chloroethylisocyandichloride 

11 

bpi" 

70-73° 

11 

29 

29. 

Methyl N-j8-bromoethyl-N-nitrosocarbamate 

53g, 182c 

bpi 

110-115° 

53g 

41, 134 

30. 

N-Bromoethylphthalimide 






31. 

/3, /S, /8-Trifluoroethylamine 





29 

32. 

/S, /3-Trifluoroisopropylamine 





29 

33. 

Methyl N-/S-chloropropylcarbamate 

7 

bp2° 

101-103° 

7 


34. 

Methyl N-/3-chloropropyl-N-nitrosocarbamate 

7 

bpO.3-0.6 

75-80° 

7 

29, 41 


SECRET 


SYNTHESIS AND PROPERTIES 


61 


Table 1 {Continued). 


Compound 

Reference 

to 

synthesis 

Physical properties 
Property Reference 

Reference to 
toxicity 
and 

vesicancy 

data 

B. Derivatives of secondary amines 

35. Ethylenimine* 

11 

bp 

54-56° 

11 

29 

36. N-Carbomethoxyethyleneimine 

7 

bpi< 

42-45° 

7 

29 

37. Propyleneimine 





.29 

38. /S-Chloroethylmethylnitrosoamine* 

182b 




134 

39 . N -/3-Chloroethyl-N -methylchloroacetamide * 






40. N-j8-Chloroethyl-N-methylcarbamyl chloride* 






41. N-/3-Chloroethyl-N-methylaminophosphoryl 
chloride 

48c 




29 

42. Ethyl-j8-chloroethylamine 

16 

bp2 

10° 

16 

29, 41 

43. Ethyl-/3-chloroethylamine hydrochloride 

16 

mp 

218-220° 

16 

29 

44. 3,5-Dimethyl-4-nitrosophenyl N-/3-chloroethyl-N- 
ethylcarbamate 

38 

mp 

84-85° 

38 

29 

45. 3,5-Dimethyl-4-nitrophenyl N-/3-chloroethyl-N- 
ethylcarbamate 

38 

mp 

42-45" 

38 

29 



bp2 

210-211° 

38 


46. 4-Nitrosothymyl N-/3-chloroethyl-N-ethylcarba- 
mate 

35 

mp 

49-50° 

35 

29 

47. 4-Dimethylaminothymyl N-/3-chloroethyl-N- 
ethylcarbamate methochloride 

35 

mp 

161-162° 

35 

29 

48. 4-Dimethylaminothymyl N-jS-chloroethyl-N- 
ethylcarbamate methiodide 

35 

mp 

165-165.5° 

35 

29 

49. N-/3-Chloroethyl-N-ethylaminophosphoryl chlo- 
ride 

48d 




29 

50. 6zs(/S-Fluoroethyl)amine* 

182e 

bp764 

123-126° 

177e 

177e 

51. 6zs(/3-Chloroethyl)amine* 

60a 




29 

52. 6zs(j3-Chloroethyl)chloramine 

11 

bp^“ 

78-80° 

11 

29, 134 

53 . his{ jS-Chloroethyl )nitrosoamine* 

7 

Cannot be distilled 

7 

29, 41 

54. 6is(/3-Chloroethyl)cyanamide 

7 

bpO.6 

123-126° 

7 

29, 41, 134 

55. Boron fluoride complex of 6is(/3-chloroethyl)amine 

50 





56 . his{ /3-Chloroethyl )methoxyamine * 





134 

57. o-Nitrobenzenesulfenyl-6is(|8-chloroethyl)amine 

32 

mp 

104-105° 

32 

29 

58. 6fs(6fs(j8-Chloroethyl)amino) sulfide 

32 

mp 

59.5-60° 

32 

29 

59. 6fs(/S-Chloroethyl)formamide 

51b 




29, 41 

60. fefs(/3-Chloroethyl)carbamyl chloride 

7 

bpO.3 

100-105° 

7 

29 

61. N,N-6fs(/8-Chloroethyl) acetamide* 

51b 




29,41 

62 . N, N s( /3-Chloroethy 1 )fluoroacetamide 

53f, 178 

mp 

64-5° 

53f, 178 




bp0.04 

102° 

53f, 178 


63. N,N-6fs(/8-Chloroet'hyl)chloroacetamide* 




64 . N , N -his{ /3-Chloroethyl )tr ichloroacetamide 

7 

mp 

CD 

7 

29, 41 

65. <e<raA:fs(/3-Chloroethyl)urea 

7 

bp2 

168-172° 

7 

29, 41 

66. Ethyl N,N-6fs(j8-chloroethyl)carbamate 





29, 41 

67. 3,5-Dimethyl-4-nitrosophenyl N,N-6fs(/3-chloro- 
ethyl )carbamate 

38 

mp 

92-93° 

38 

29 

68. 3,5-Dimethyl-4-nitrophenyl N,N-6fs(/3-chloro- 
ethyl)carbamate 

38 

mp 

58-59.5° 

38 

29 

69. 4-Nitrosothymyl N,N-6fs(/3-chloroethyl)carba- 
mate 

35 

mp 

111-112° 

35 

29 

70. 4-Nitrothymyl N,N-6fs(j8-chloroethyl)carbamate 

35 

mp 

58-58.5° 

35 

29 

71. 4-Dimethylaminothymyl N,N-6fs(/3-chloroethyl)- 
carbamate methochloride 

35 

mp 

153-154° 

35 

29 

72. 4-Dimethylaminothymyl N,N-5fs(|S-chloroethyl)- 
carbamate methiodide 

35 

mp 

154-155° 

35 

29 

73. N,N-5fs(/8-Chloroethyl)amino dichlorophosphine 

11 

bp^“ 

130-137° 

11 

29 

74. N ,N-6fs( /3-Chloroethyl )amino-6fs( /8-chloroethyl- 
thio)phosphine 

48e 





75. N,N-6fs(/3-Chloroethyl)aminophosphoryl fluoride 

48e 




29 

76. N,N-5zs(/3-Chloroethyl)aminophosphoryl chloride 

53f 

mp 

54°’ 

53f 


77. Methyl 5fs(/8-chloroethyl)amidocyanophosphate 

60d 




106b 


SECRET 


62 


NITROGEN MUSTARDS 


Table 1 {Continued). 

Reference to 


Compound 

Reference 

to 

synthesis 


Physical properties 

Property Reference 

toxicity 

and 

vesicancy 

data 

78. Dimethyl 6is(j8-chloroethyl)amidophosphate 

60d 




106b 

79. Diethyl N,N-&is(/3-chloroethyl)amidophosphate 

53h 

bp^° 

164-165.5° 

53h 

29 

80. 6zs(/3-Chloroethylthio)-N,N-6is(/3-chloroethyl)- 

48f 


1.5525 

48f 

29 

amidophosphate 



1.472 

48f 




bpO.Ol 

155-160° 

48f 


81. Ethyl chloracetiminoester hydrochloride 

11 

mp 

90-100°(dec.) 

11 

29, 41 

82. N-/3-Chloroethylaniline 

11 

bp^ 

80° 

11 


83. N,N'-6is(/3-Chloroethyl)-p-phenylenediamine 

42 

mp 

79° 

42 

29, 41 

84. N,N'-his(/3-Chloroethyl)-p-phenylenediamine di- 
hydrochloride 

42 

mp 

212°(dec.) 

42 

29, 41 

85. N,N '-his(i8-Chloroethyl)-N,N '-dinitroso-p-phen- 
ylenediamine 

42 

mp 

106.5° 

42 

29, 41 

86. N, W-bis (/3-Chloroethyl) -N, N'-dicarbethoxy-p- 
phenylenedi amine 

42 

mp 

102-103° 

42 

29, 41 

87. 2-(/3-Chloroethylamino)quinoline hydrochloride 

48g 

mp 

149-152° 

48g 

29, 41 

88. a!-Benzylamino-i8-chloro-/3-pheny Ipropi ophenone 
hydrochloride 

47 

mp 

152-156° 

58 

29 

89 . jS-Benzylamino-a-bromo-jS-phenylpro piophen one 
hydrobromide 

47 

mp 

147-149° 

58 

29 

90. a-Benzylamino-/3-bromo-/3-phenylpropiophenone 
hydrobromide 

47 

mp 

144-147° 

58 


C. Derivatives of tertiary amines 

91. N -Methylethyleneimine 





29 

92. /3-Ethyleneiminopropionitrile 

53j 

bp^2 

67-69° 

53j 

29 

93. Methyl /3-ethyleneiminopropionate 

53j 

bp^" 

61-64° 

53j 

29 

94. /3-Chloroethyldimethylamine* 





134 

95. Dimethyl /3-chloropropylamine 

16 


1.4214 

16 

29, 41 




0.899 

16 




bp3^ 

36.5-38° 

16 


96. Dimethyl /S-chloropropylamine hydrochloride 

16 

mp 

170-174° 

16 


97. Methyl 6is(/3-fluoroethyl)amine* 


bp 

123-124° 

177e 

177e 

98. Methyl 6zs(/3-chloroethyl)amine* 

2, 5 

nvf^ 

1.4679 

2 

29, 41, 121, 




1.4682 

115 

134 



d?^ 

1.118 

82 





1.1203 

115 




bp2o 

50.0-50.5° 

2 




vopo 

2.487 

15 


99. Methyl 6is(/3-chloroethyl)amine hydrochloride* 

2 

mp 

107-108° • 

2 

29, 41, 129, 

100. Methyl 6ts(/3-chloroethyl)amine formate 

51a 




177a 

101. Methyl 6js(j8-chloroethyl)amine picrate 

51a 





102. Boron fluoride complex of methyl-6^s(/3-chloro- 
ethyl)amine 

50 





103. Reaction product of methyl 6is(/3-chloroethyl)- 
amine and titanium tetrachloride 

51c 





104. Methyl 6zs(/3-chloroethyl)amine oxide hydro- 
chloride 





29 

105. Methyl 6is(/3-cyanoethyl)amine 

53e 

bpi° 

177-187° 

53e 

29 

106. Methyl 62 s(/ 3 -thiocyanoethyl)amine 

23 

Decomposition on distilla- 

23 

29 

107. Methyl 6is(j8-thiocyanoethyl)amine hydrochloride 

23 

tion at 1.5 mm 
mp 117-118° 

23 

29, 41 

108. Methyl /3-chloroethyl-/3-hydroxyethylamine 

12, 126 




29, 41 

109. Methyl /3-chloroethyl-j3-hydroxyethylamine hy- 
drochloride 

12 




29 

1 10. Methyl /3-chloroethyl-/3-hydroxyethylamine picrate 

12 

mp 

72-73° 

12 


111. Methyl /3-acetoxyethyl-j3-chloroethylamine* 

32, 126 


1.4474 

32 

43, 106b 



bpO.l® 

54° 

32 




bpO.io 

46° 

32 




bpO.08 

41° 

32 



SECRET 


SYNTHESIS AND PROPERTIES 


63 


Table 1 {Continued). 






Reference to 


Reference 




toxicity 


to 


Physical properties 


and 

Compound 

synthesis 

Property Reference 

vesicancy 






data 

112. Dimethyl /3, jS'-dichloro-^erf-butylamine* 

113. Methyl /3-chloroethyl-/3-chloropropylamine* 





ik 

1 14. Methyl /3-chloroethyl-j8-chloropropylamine* 

115. Diethyl j8-chloroethylamine* 

116. Diethyl /8-chloroethylamine hydrochloride 

16 

mp 

210-211.5° 

16 

134 

117. Ethyl 6zs(/3-chloroethyl)amme* 

2, 10, 120 


1.4639 

2 

29, 41, 134, 



0 



143 



d 

1.083 

2 




bpi-6 

49.0-49.5° 

2 




vopo 

1.59 

31 


118. Ethyl 6zs(/3-chloroethyl)amine hydrochloride* 

119. Ethyl j8-chloroethyl-j8-hydroxyethylamine picryl- 

2, 10 

mp 

139-140° 

2 

137 

sulfonate 

17 

mp 

110-111° 

17 

29 

120. /3-Methoxyethyl 6is(jS-chloroethyl)amine 

23 


1.4671 

23 

29, 41 




1.108 

23 


121. /3-Methoxyethyl-6fs(/3~chloroethyl)amine hydro- 






chloride 

23 

mp 

133.5-134.5° 

23 


122. /m(j8-Chloroethyl)amine 

2, 5, 156 


1.4962 

156 

29, 41, 
118, 156 



bp* 

127° 

156 




bp^* 

141° 

156 




mp 

3.7° 

156 




voP* 

0.0779 

31 


123. fn's(/3-Chloroethyl)amine hydrochloride 

2, 156 

mp 

130-131° 

2 

29, 41, 156 

124. Boron fluoride complex of ^m‘(/3-chloroethyl)amine 

125. <m(/3-Chloroethyl)liydroxy ammonium chloride* 

126. <m(/3-Thiocyanoethyl)amine 

50 




106c 

127. /3-[6fs( /3-Chloroethyl)amino]propionitrile 

23 


1.4900 

23 

29, 41 




1.151 

23 




bp2° 

126-130° 

23 


128. i3-[6fs(i8-Chloroethyl)amino]propionitrile hydro- 






chloride 

23 

mp 

89.5-90.5° 

23 


129. N-i3-Chloroethylmorpholine* 

11, 23, 200 

bp23 

102-106° 

11, 31 

29, 134 



voP* 

1.792 



1 30. N-/3-Chloroethylthiomorpholine* 

11 

bpO.5 

77-80° 

11 

29 

131. N-/3-Chloroethylthiomorpholine hydrochloride* 

132. N-/3-Chloroethylthiomorpholine sulfone* 

133. N-j8-Chloroethylthiomorpholine sulfone hydro- 

11 

mp 

208-209° 

11 


chloride* 






1 34 . Methyl-6f s( y-chloroallyl )amine * 

135. Methyl-6f s( /3-chloropropyl )amine * 

16, 130 


1.5147 

16 

41, 134 




1.027 

16 




bp2'‘ 

55-57° 

16 




VOpO 

1.898 

31 


136. Methyl-6fs( /3-chloropropyl )amine hydrochloride 

16 


.... 



137. 2-Propy nyl-5f s( /3-chloroethy 1 )amine 

32 


1.4915 

32 

29 




1.139 

32 




bpi 

63-64° 

32 


138. 2-Propynyl-6fs(/8-chloroethyl)amine hydrochloride 

32 





1 39. Allyl-6f s( /3-chloroethyl )amine* 

2, 23 


1.4739 

2 

29, 134, 148 



d 

1.075 

2 




bp3 

80° 

148 




bp2 

62-63° 

2 


140. Allyl-6fs(j8-chloroethyl)amine hydrochloride* 

2, 23 

mp 

91-92° 

23 


141. j8-Chloroallyl-6zs( /3-chloroethyl )amine 

32 

bp2 

85-87° 

32 

29 

142. /3-Chloroallyl-6zs( /3-chloroethyl )amine hydrochloride 

32 

mp 

105-106.5° 

32 


143. Propyl 6fs(/3-chloroethyl)amine* 

16, 120 


1.4629 

16 

29, 41, 134, 






143 




1.092 

16 

148 



bp^ 

62-63° 

16 




vopo 

0.783 

31 



SECRET 


64 


NITROGEN MUSTARDS 


Table 1 {Continued). 


Reference to 
toxicity 

PhysiCcal properties and 

Property Reference vesicancy 

data 


144. Propyl 5is(j8-chloroethyl)amine hydrochloride* 

16, 120 

mp 

118-120° 

16 

137 

1 45 . i8-Chloropropyl-6f s( /3-chloroethy 1 )amine* 

146 . Isopropyl-6f s( /3-chloroethyl )amine * 

2,9 


1.4641 

* 2 

29, 41, 143 



d 

1.053 

2 




bp2-5 

67.0-68.0° 

2 




mp 

13.7 

83 




VOpO 

0.869 

15 


147. Isopropyl-6fs( /3-chloroethyl )amine hydrochloride* 

2,9 

mp 

210-213°(dec.) 

2 

41, 137 

148. N-/8-Chloroethylpiperidine 

11 

bp2 

40-41° 

11 

29, 41 

149. N-/3-Chloroethylpiperidine hydrochloride 

11 

mp 

230° 

11 


150. Butyl- 62 's(/ 3 -chloroethyl)amine 

16 


1.4637 

16 

29, 41 




1.027 

16 




bp2® 

89.0-89.5° 

16 




vopo 

0.321 

31 


151. Butyl-6fs(/3-chloroethyl)amine hydrochloride 

152. 7 -Chlorobutyl-6zs(j8-chloroethyl)amine 

16 

mp 

96-97° 

16 

29, 41 

153. 7 -Oxobutyl 6is( /3-chloroethyl )amine hydrobromide 





29 

154. sec-Butyl-6is(/8-chloroethyl)amine 

16 


1.4655 

16 

29, 41 



d?^ 

1.028 

16 




bpi 

84-84.5° 

16 




vopo 

0.394 

31 


155. sec-Butyl-6fs(/8-chloroethyl)amine hydrochloride 

16 

mp 

132-138° 

16 


1 56 . Isobutyl-6f s( /3-chloroethyl )amine 

16 


1.4597 

16 

29,’ 41 




1.0078 

16 




bp^ 

81-81.3° 

16 




vopo 

0.508 

31 


157. Isobutyl-6fs(/8-chloroethyl)amine hydrochloride 

16 

mp 

107-108° 

16 


158. <er<-Butyl-5f s( /3-chloroethyl )amine 

16 


1.4710 

16 

29, 41 




1.032 

16 




bp^® 

68-69° 

16 




vopo 

0.581 

31 


159. <er<-Butyl-6is( /3-chloroethyl )amine hydrochloride 

160. /3, /3', /3"-Trichloro-^er<-butyl 6fs( /3-chloroethyl )- 

16 

mp 

176.5-177.5° 

16 


amine 

23 


1.5226 

23 

29 




1.302 

23 




bp2« 

138-140° 

23 


161. /3, /3', /3"-Trichloro-<er<-butyl 6is( /3-chloroethyl )- 






amine hydrochloride 

23 

mp 

112.2-114.2° 

23 

41 

1 62. /3-Chloroethyl-6is( j3-chloropropyl )amine* 

163. /3-Chloroethyl-6fs(/8-chloropropyl)amine hydro- 






chloride* 






164. Furfuryl 6is( /3-chloroethyl )amine 

23 

no^® 

1.5033 

23 

41 



d2® 

1.171 

23 




bp3.5-4.0 

106-107° 

23 


165. Furfuryl-6fs(/3-chloroethyl)amine hydrochloride 

23 

mp 

88.5-89.5° 

23 

29, 41, 43 

1 66 . Tetrahy drof urf uryl-6f s( /8-chloroethyl )amine 

23 


1.4877 

23 

29, 43 




1.129 

23 




bpO.® 

82-84° 

23 


167. Tetrahydrofurfuryl-5fs(/3-chloroethyl)amine hy- 





drochloride 

23 

mp 

117-118° 

23 


168. di-N-(/3-Chloroethyl)-2-chloromethylpiperidine 





hydrochloride* 






169. 6(or 7)-Chloroetronecane 

30 

no'® 

1.4913 

30 

29 



bp®" 

111-112° 

30 


170. 6(or 7)-Chloro-l-chloromethyl-l,2-dehydropyr- 





rolizidine hydrochloride 

30 

mp 

122-123° 

30 

29 

171. fm(/3-Chloropropyl)amine 

11 

bp® 

99-103° 

11 

29 

172. N-Ethyl-N -( /3-chloroethyl )aniline 

11 

bp"-^ 

102-109° 

11 

29, 41 

173. N,N-6fs(/8-Chloroethyl)aniline* 

11 

bp°-7 

123° 

11 

29, 41 



mp 

43-44° 

11 



Compound 


Reference 

to 

synthesis 


SECRET 


SYNTHESIS AND PROPERTIES 


65 


Table 1 {Continued). 

Reference to 

Reference toxicity 

to Physical properties and 

Compound synthesis Property Reference vesicancy 

data 


174. N,N-6fs(iS-Chloroethyl)-p-nitrosoaniline 

175. Cy clohexyl-6fs( /3-chloroethyl )amine 


176. Cyclohexyl-6fs(/3-chloroethyl)amine hydrochloride 

1 77. Benzyl-6fs( /3-chloroethyl )amine 


178. Benzyl-6fs(i8-chloroethyl)amine hydrochloride 

179. Heptyl-6fs( /3-chloroethyl )amine 

180. Heptyl-6fs( /3-chloroethyl )amine hydrochloride 

181 . Phenethyl-6fs(j8-chloroethyl)amine 

182. N, N, N', N'-<e<mA:is(j8-Chloroethyl)ethylene- 

diamine dihydrochloride 

183. l,3-6fs(5fs(/3-Chloroethyl)amino) propane dihydro- 

chloride 

184. 1, 3-6fs[6fs(/8-Chloroethyl)amino]-2-chloropropane 

dihydrochloride 

185. 6fs[/3-( 6fs(/8-Chloroethyl)amino)-ethyl] sufide* 

186. 5fs[/3-(6fs(/3-Chloroethyl)amino)-ethyl] sulfide 

dihydrochloride 

187. N,N'-6fs(/3-Chloroethyl)-N,N'-dimethyl-p- phenyl- 

enediamine 

188. 2-Chloromethylpyridine 

189. 2-Chloromethyl-5-methoxy-7-pyridone hydro- 

chloride 

190. 2-(/3-Chloroethyl)pyridine 

191. 2-(/3-Chloroisopropyl) pyridine hydrochloride 

192. N-/3-Chloroethylcarbazole 

193. 3,6-Dibromo-N-j8-chloroethylcarbazole 

194. N-/3-Chloroethylacridan 

195. N-/3-Chloroethylphenothiazine 

D. Derivatives of quaternary ammonium salts 

196. Trimethyl-/3-fluoroethylammonium bromide* 

197. Dimethyl-6is(j8-chloroethyl)ammonium chloride 

198. /3-Acetoxyethyl-/3-chloroethyldimethylammonium 

iodide* 

199. Methyl-<m(/8-chloroethyl)ammonium chloride* 

200. Methyl-<m(i9-chloroethyl)ammonium sulfate* 

201. Ethylvinyl-6is(/8-chloroethyl)ammonium chloride 

202. Triethyl-/3-fluoroethylammonium bromide* 

203. /3-Carbamoxyethylethyl-6fs(/3-chloroethyl)ammo- 

nium chloride 

204. /3-Fluoroethylpyridinium bromide* 

205. N,N-6fs(/3-Chloroethyl)piperidinium chloride mono- 

hydrate 

206. Polymer of me thyl-6fs( /3-chloroethyl )amine (n = 2) 

207. Polymer of methyl-6fs(/3-chloroethyl)amine 

208. l,4-^>fs(/3-Chloroethyl)-l, 4-die thylpiperazinium di- 

chloride 

209. Ammonium compound from 1 mole of methyl-6is(/3- 

chloroethyl)amine and 2 moles of methyldi- 
ethanolamine 


53c 

mp 

72° 

53c 

29, 41 

16 


1.4940 

16 

29, 41 



1.077 

16 



bpi-^ 

105-105.6° 

16 



vopo 

0.0383 

31 


16 

mp 

174-175° 

16 


16 

nD“ 

1.5334 

16 

29, 41 



1.112 

16 



bp2 

138-139° 

16 


16 

mp 

147.2-148.2° 

16 

41 

2 

d 

<1.0 

2 

29 

2 




41 

53g 

bp* 

96° 

53g 

29 

49 




29, 41 

32 

mp 

138-139° 

32 

29 

32 

mp 

141-141.2° 

32 

29 

23 


1.5287 

23 

29 


mp 

24.2-24.7° 

23 


23 

mp 

137-138° 

23 

29, 41 

42 

mp 

61° 

42 

29 

53b 





53d 

mp 

155° 

53d 


11 

bp°-2 

57° 

11 


53i 

mp 

122° 

53i 


59 

mp 

130-131° 

59 

29, 41 

48a 





48b 





48b 







mp 

244° (dec.) 

177d 

177d 





29, 41 

126 

mp 

150° (dec.) 

126 


32 

mp 

192-196° (dec.) 

32 

29 


mp 

237° (dec.) 

177c 

177c 

23 




29, 41 


mp 

180° 

177c 

177c 

2 




29 

2 




29 





29 





29 


Detailed studies of the preparation of the four pilot plant, or manufacturing scale are reported in 
most important nitrogen mustards on a laboratory, the following references. 


SECRET 


66 


NITROGEN MUSTARDS 


Agent 

HNl 

HN2 

HNS 

Isopropyl-6is(/3- 

chloroethyl)amine 


References 

2, 4, 10, 74, 87, 95, 97, 98, 99, 136, 182d 
2, 4, 5, 82, 120, 158, 160, 182a, 185a, 
185b, c, d, 192, 194, 196 
2, 4, 5, 68, 80, 92, 96, 157, 170, 171, 172 

2, 4, 83, 136 


Work has been done on alternate syntheses which 
do not employ thionyl chloride. Results have been 
discouraging. 2 The best alternate method for 
HNl uses phosphorous trichloride in place of thionyl 
chloride, and gives yields approaching 75 per cent.^® 
Other reagents used with less success are phosphorous 
pentachloride,^®® phosgene,^*^’"’'^’^®^ and hydrochloric 
acid.^®^*^ 

The alkyl-6fs(i8-hydroxy ethyl) amines and tris{^- 
hydroxyethyl) amine required for synthesis of the 
nitrogen mustards have been prepared commer- 
cially by reaction of primary amines or ammonia 
with ethylene oxide. Some work has been reported 
in the classified literature on such reactions and on 
the purification of technical ethanolamines for use as 
nitrogen mustard intermediates.®*’^®®'^®®-^®^’^®^’^®^-^®*- 

169,172,185a.e,192,194,196 

Because of the possibility of a short supply of 
ethylene oxide in the event of large-scale nitrogen 
mustard manufacture, methods which did not em- 
ploy ethylene oxide were investigated for preparing 
alkanolamines, particularly RN(CH 2 CH 20 H )2 (where 
R is ethyl, methyl, or isopropyl). The most success- 
ful method developed utilizes formaldehyde, hydro- 
gen cyanide, and ethyl alcohol as the basic raw 
materials and follows these steps : 

1. HCN -h CH 2 O ^ CH 2 OHCN 

2. CH2OHCN -f (C2H50)2CH2 — ^ 
C2H5OCH2OCH2CN -h C2H5OH 

3 . 2C2H5OCH2OCH2CN + 4H2 
(C2H50CH20CH2CH2)2NH -h NH3 

4. 2(C2H50CH20CH2CH2)2NH -h (C2H5)2S04 

+ Na2C03— > 2(C2H50CH20CH2CH2)2NC2H5 

+ Na2S04 + H2O -f- CO2 

5. (C2H50CH20CH2CH2)2NC2H5 + HCl 

+ C2H5OH — ^ (CH20HCH2)2NC2H5 HC1 

+ 2CH2(0C2H5)2 

This “formal” route, in which formaldehyde 
cyanohydrin is converted to a less sensitive formal 
derivative before hydrogenation, is estimated to be 
capable of producing N-ethyl diethanolamine hydro- 
chloride at a cost of 25 to 30 cents per pound, at an 
annual rate of 10,000,000 pounds. A more direct 


route, in which formaldehyde cyanohydrin is hydro- 
genated directly to diethanolamine (subsequently 
alkylated), gave poorer yields and appears to be a 
more expensive process. Methyl-5fs(j8-hydroxy- 
ethyl)amine has been prepared successfully by hy- 
drogenation of diethanolamine in the presence of 
formaldehyde.^^ Other less advantageous routes to 
the alkanolamine intermediates for HNl, HN2, and 
HN3 have been explored. In addition to the stand- 
ard method of preparation from isopropyl amine and 
ethylene oxide, isopropyl-6fs (/3-hydroxy ethyl) amine 
has been prepared by hydrogenation of a mixture of 
acetone and diethanolamine,^® or by the reaction of 
ethylene oxide with isopropyl-/3-hydroxyethylamine. 
The latter compound is prepared by hydrogenating 
a mixture of acetone and ethanolamine.^®® 

6.2.2 Physical Properties 

The nitrogen mustards are oils of limited water 
solubility. They are miscible with ordinary organic 
solvents. Their physical properties have been ex- 
tensively studied 2 >®> ^ ,26 ,31 ,52 , 80 , 82 , 83 , 87 ,115 ,118 , 156 ,164 , 

167, 168 , 169,1 83b, c gome of the constants having most 
bearing on chemical warfare are presented in Table 2. 

6.2.3 Chemical Properties 

The nitrogen mustards are basic amines which 
form stable salts with strong acids such as hydro- 
chloric acid. They are active alkylating agents, and 
the physiological reactions responsible for their 
toxicity are primarily alkylations. Their reactions 
from the biochemical, physicochemical, and physi- 
ological mechanism standpoints have been studied 
in great detail and are summarized in Chapters 19, 
20, and 21. A primary intermediate in their reactions 
is a l-(i3-chloroethyl)ethylenimonium ion, formulated 
below for HN2, which is analogous with the ethylene- 
sulfonium compound^ intermediate in the reactions 
of H (see Chapters 19 and 20).3-'‘-8-i3,i4,i7.i8,24, 26 , 33 . 122 , 

125, 127, 130, 135, 151, 181a, b 

Self-alkylation is responsible for the dimerization 
which occurs slowly when the lower molecular weight 
alkyl-6zs (/3-chloroe thy 1) amines are allowed to stand. 
The reaction is rapid in the presence of water. It re- 
sults in the deposition of crystalline solids such as the 
“dichlorocyclic dimer” which is formed from HN2: 


‘’Ethylene-Sulphonium Compound CICH 2 CH 2 

+ 

SCH 2 CH 2 CI- 


SECRET 


SYNTHESIS AND PROPERTIES 


67 


Table 2. Physical properties of HNl, 

HN2, HN3, and isopropyl- 62 s(j 8 -chloroethyl)amine in comparison 

with those of H. 

Property 

H 

HNl 

Agent 

HN2 

HN3 

Isopropyl- 62 s(/ 3 - 
chloroethyl )amine 

Molecular weight 

159 

170 

157 

204.6 

184 

Freezing point (C) 

14.231 

-33+67.88 

_7Q _|-82,91,115 

_3 16,80,188 

13.763 

Density (g/ml at 25 C) 

1.2767 

1.0967 

1.1262 

1.2315,60,188 

1.0532 

Vapor pressure (mm Hg) 

at IOC 

0.0319*-3i 

0.077331 

0.130tt 

0.00272 §.31 

0.0364616 

at 25 C 

0.112 

0.250t 

0.427 

0.0109 

0.130 

at 40 C 

0.346 

0.722 

1.25 

0.0382 

0.410 

Volatility (mg/l) 

at IOC 

0.288*-3i 

0.74431 


0.0315§-3i 

0.3806.76 

at 25 C 

0.96 

2.29 

2.58 

0.120 

1.29 

at 40 C 

2.83 

6.29 

10.0 

0.400 

3.87 


* The values are in good agreement with those reported in reference 183a. 
t Compare 0.239 mm Hg at 25C.*^ 

X Compare reference 183b. 

§ Compare 0.0656 mg/l at 25C,**® 0.011 mm Hg at 25C,i®3c 0.014 mm Hg at 25C,>*^ and 0.112 mg/l at 25C.® The values reported in reference 
15 are now believed to be too high. 


CH2CH2CI CH2CH2 

/ +/ I 

CHr-N H2O CH3— N 1 + Cr 

\ \ 

CH2CH2CI CH2CH2CI 

1 -met hy 1- 1 ( /3-chloro- 
HN2 ethyl )ethylenimonium 

chloride 

Cl- CH2CH2 Cl- 

+/ \+ 

dimerization^ nir'K^OH^N NCH2CH2CI 

l\ /I 

CH3 CH2CH2 CHs 
“dichlorocyclic dimer” 
(N,N'-dimethyl-N,N'-6is- 
( )8-chloroe thy 1 )piper- 
azinium dichloride) 

6.2.4 Stability 

Storage Stability 

The al kyl-62s (i3-ch loroe thy 1) amines as a class 
dimerize on storage and deposit crystalline dimers 
at rates which decrease with increasing size and 
branching of the alkyl group. The stabilities of many 
of the nitrogen mustards prepared for toxicological 
examination have been measured by heating them 
in closed systems at 60 C and determining the rate 
of formation of solid dimer.^-^-io.ie.ss xhe rate of 
dimerization is not appreciably accelerated in the 
presence of steel, brass, or solder. In the cases 
of HNl and HNS pressure development is not a 
problem. 

HNS is the most stable of the more important 
nitrogen mustards. It slowly deposits a crystalline 
dimer on long standing at elevated temperatures, but 


the rate is so slow if the agent is dry that its storage 
stability can be considered so good as to offer no 
practical limitations on its use as a chemical warfare 

agent.ioo-ii2.ii8.i73 

HNl is also considered to be sufficiently stable for 
storage but the margin of safety is much less than in 
the case of HNS and the use of stabilizers is neces- 
sary or desirable. The amine should be dry for maxi- 
mal stability; addition of 10 per cent kerosene ^ plus 
1 per cent hexamethylenetetramine 2’ as stabilizers 
has been recommended. 

HN2 was originally considered sufficiently stable 
for use in temperate climates by the British, I'l^ but 
the low stability of production lots of this agent and 
the occurrence of an explosion during storage in one 
instance have led to a revision of this point of view. 
In one investigation HN2 was found to be only one- 
sixth as stable as HNl.^ 

Isopropyl-6fs (d-chloroe thy 1) amine was found to be 
25 times as stable as HNl.'* 

HNl and HNS can be satisfactorily thickened 
with various polymeric materials.^'* 

Stability on Explosion in Munitions 

The explosion stabilities of HNl, HN2, and HNS 
appear to fall in the same order as their stabilities 
upon storage. All available evidence indicates that 
HNS is exceedingly stable, certainly not inferior to 
H in this regard. HNS-filled 105-mm shell, 75-mm 
shell, HE/Chem. 6-inch howitzer shell, and M47A2 
bombs have been exploded without qualitative evi- 
dence of decomposition of the charging.®® 

The plan of the Germans to use HNS in high ex- 
plosive-chemical shell offers confirmatory evidence. 


SECRET 


68 


NITROGEN MUSTARDS 


HNl is certainly less stable than HNS, although 
not necessarily so much more so as to negate its prac- 
tical use as a chemical warfare agent. HNl-filled 
75-mm shell, 4.2 chemical mortar shell, and M70 
bombs have been exploded without evidence of gross 
decomposition except in 75-mm shell under condi- 
tions more severe than are encountered in the 
field.®** However, in the most quantitative in- 
vestigation that has been made, one of six M47A2 
bombs charged HNl flashed on static detonation.®® 
Although considerable toxicologically effective vapor 
was subsequently evolved from the terrain contam- 
inated by the explosions in these tests, the dosages 
were less by an amount approaching 30 per cent than 
would have been predicted from similar tests with H 
had no decomposition of HNl occurred during the 
explosion or, subsequently, on the contaminated 
terrain.®® 

The available data for HN2 are of a rather quali- 
tative nature. It appears that this agent can be dis- 
persed without complete destruction by explosion of 
various chemical munitions but that the toxicological 
effects of the initial clouds so produced are inferior to 
those produced by H or 

Stability on Terrain 

Two important characteristics determining rate of 
inactivation on soil and vegetation are solubility in 
water and rate of reaction with water. The approxi- 
mate data given in Table 3 lead to the prediction of 


Table 3. Characteristics influencing rate of inactivation 
of H, HNl, HN2, and HNS on terrain. 


Agent 

Approximate solubility 
in water at room tem- 
perature (ppm) 

Approximate half- 
life in water at 

25 C 

(minutes) 

H 

500 

8 

HNl 

4,000 ± 

1.3 

HN2 

13,000 ± 

4.0 

HN3 

80 

2.4 


greater losses with HNl and HN2 than with HN3 
and H. This prediction is confirmed by the available 
field data. There is no evidence in the semi quanti- 
tative data of bomb and annulus trials that losses on 
moist terrain are greater for HN3 than for H, in 
spite of the greater persistence of HN3.®® The results 
of British annulus trials with HNl and HN2 on 
alkaline sod (Porton downland) indicate that ground 
losses are significantly greater than in the case 
of H.**®’*®® Although the initial dosages of evolved 


HNl and HN2 vapor were greater than those of H, 
as predicted from the relative volatilities, the total 
dosage {Ct) of evolved vapor was in the cases of HN 1 
and HN2 only one-half of that anticipated from 
similar trials with H. In annulus trials with HNl 
and H in Florida, large drops were used on relatively 
dry terrain and the 4-hour vapor dosages failed to 
reveal significantly greater ground losses for HN3 
than for H.®® As stated above, however, in trials with 
single, statically fired bombs the vapor evolution of 
HNl was somewhat less than would have been pre- 
dicted on the basis of tests with H. Part of the loss 
may have occurred during the explosion of the 
bombs, and part subsequently on the terrain. Ter- 
rain losses would have been facilitated by the dis- 
persion of the agent into small droplets during the 
explosion. 

6.2.5 Detection and Analysis 

Excellent methods for the detection and analysis 

of the nitrogen mustards are available (see Chap- 
ters 34 and 37). 

For purposes of detection the use of the DB-3 re- 
agent (see Chapter 34) is perhaps the most useful. 
As used in the United States M9 Detector Kit, this 
test is approximately as sensitive for the nitrogen 
mustards as for H. Collection of 0.1 to 0.2 ;ug of HNl, 
HN3, or H from air containing 0.2 ng/X or more of 
these agents suffices to give a positive reaction . **2 A 
supplementary test to differentiate nitrogen mustard 
from H is somewhat less sensitive. 

For purposes of analysis, among the most useful 
methods are those utilizing the DB-3 reagent and 
those dependent upon the mercurimetric titration of 
the chloride obtained by hydrolysis from the nitro- 
gen mustard (see Chapter 37). 

6.2.6 Decontamination and Protection 

The gas mask canister offers complete protection 
against the nitrogen mustards. 

In general, standard methods of decontamination 
effective for H are useful for the nitrogen mustards, 
but destruction of the nitrogen mustards by chemical 
reaction with bleach or with currently used chlor- 
amides is notably less efficient and rapid than in the 
case of H (see Chapters 24 and 32). 

6.3 CHEMICAL STRUCTURE IN RELA- 
TION TO TOXICOLOGICAL POTENCY 

Among the nitrogen mustards and related com- 
pounds that have been studied (see Table 1), the 


SECRET 


TOXICOLOGY 


69 


highest toxicological potency is found among the 
tertiary (jS-chloroe thy 1) amines, and, in particular, 
in HNl, HN2, HNS, and the propyl and isopropyl 
analogs of HNl. The toxicity, vesicancy, and eye- 
injurant action of these compounds is reviewed in the 
following sections. 

6.4 TOXICOLOGY 

6.4.1 Detectability by Odor and 
Sensory Irritation 

HNl, HN2, and HNS are markedly less detectable 
by odor or sensory irritation than is H. Testimony 
to the insidiousness of the vapors of all three nitrogen 
mustards comes from plant accidents in which men, 
informed of the potential hazard, were incapacitated 
without being aware of having been exposed until 
eye and respiratory symptoms developed after a 
lapse of several hours. 

Laboratory (osmoscopic) determinations of the 
median detectable concentrations of H, HNl, HN2, 
and HNS are given in Table 4. Attention is directed 


Table 4. Median detectable concentrations of H, HNl, 
HN2, and HNS as determined in the laboratory by the 
osmoscopic technique. 


Agent 

Purity 

Median detectable 
cone. (Mg/1) 

Reference 

H 

Plant run Levinstein 

0.6 

90 


Vacuum-distilled 

1.2 

102 


Thiodiglycol 

1.8 

102 

HNl 

Plant run 

13 

90 


Pure 

17 

85 

HN2 

Pure 

38 

76 

HNS 

Plant run 

15 ± 

104a 


Pure 

? 



only to the relative values because the absolute mag- 
nitudes of the concentrations are not necessarily of 
significance for field conditions. Median detectable 
concentrations as determined in a man-chamber 
were for H in the order of 1 /ig/l or even less; 
for HN2, IS Mg/1; and for HNS, 8.5 Mg/b'^® 

HNl and HN2 possess faint “fishy or soapy’’ 


® Use of a technique in which observers in the field walked 
upwind toward a source of HN 1 vapor until they detected an 
odor and then took a sample of air for analysis revealed that 
this agent could be detected at an average concentration in air 
of 0.02 Mg/1, although the characteristic fishy odor was ap- 
parent only at much higher concentrations.^®® Presumably 
use of this technique with H and other nitrogen mustards 
would give values correspondingly low in relation to the 
median detectable concentrations as determined in the labora- 
tory. 


odors. The pilot plant HNS that was made in Eng- 
land has a faint geranium-like odor. Inasmuch as 
oral reports indicate that laboratory-prepared sam- 
ples do not possess this odor, it may be suspected 
that the geranium-like odor was due to an impurity, 
possibly associated with the preparation of the ma- 
terial in equipment previously used for lewisite. This 
pilot plant material was used in the osmoscopic de-. 
termination cited in the preceding paragraph. Thus, 
it is possible that other samples of plant run HNS 
would be even more odorless, and therefore more 
insidious. 

6.4.2 Toxicity 

Toxicity data for animals totally exposed to air- 
borne HNl, HN2, and HNS are set forth in Tables 6, 
7, and 8. From the summary presented in Table 5 it 


Table 5. Summary of toxicities of H, HNl, HN2, and 
HNS in the form of vapors. 

(See Tables 6, 7, and 8 of this chapter and Table 5 of 
Chapter 5 for more detailed data.) 


Agent 


L{Ct)oo (mg min/nP) 

Mouse* Range for 

(^ = 10 min) other species f 


Estimated 
relative 
toxicity 
(H = 100) 


H 

1,100 

600-2,800 

100 

HNl 

900 

500-3,000 

?=J100 

HN2 

2,600 

1,000-6,000 

50 

HN3 

550 

500-2,000 

>100 


* Fifteen-day observation period, 
t Approximate. 


appears that, considering all species, HNS is some- 
what more toxic than H, HNl about as toxic as H, 
and HN2 about one-half as toxic as H. 

The nominal LCso’s of propyl-6fs(i8-chloroethyl)- 
amine and isopropyl-6fs(|S-chloroethyl) amine for mice 
exposed 10 minutes and observed 10 to 12 days 
are 0.16 to 0.17 mg/l.^®’*^ These figures, as well as 
less complete data for larger species,'^'^^’^'^^ indicate 
that the propylamines possess toxicities intermediate 
between those of HNl and HN2. References to 
toxicity data for other nitrogen mustards and related 
compounds are given in Table 1. 

The L(C0 5 o’s of HNl, HN2, and HNS appear to 
be relatively independent of exposure time over the 
range from a few minutes to several hours (see 
Tables 6, 7, and 8). 

Mortality data for animals exposed to the nitrogen 
mustards often exhibit great variability.^^ 

139,140,143 Among the factors which may contribute to 
this variation are presence of aerosol, wind speed or 


SECRET 


70 NITROGEN MUSTARDS 


Table 6. Toxicity of HNl. The animals were totally exposed. LfCOso’s that 
given in parentheses. 

are estimated very approximately are 

Species 

L(CtU 

(mg min/m^) 

Exposure 

time 

(min) 

Observation 

period 

(days) 

Analytical 

(A) 

or 

nominal 

(N) 

cone. 

Number 

of 

animals 

Notes 

Reference 

Mouse 

900 

10 

15 

A 

280 

Low-flow chamber 

37 


900 

10 

15 

A 

89 

High-flow chamber 

37 


1,300 

10 

10 

N 

140 

Low-flow chamber 

85 


<1.200 

30 

15 

A 

30 

Static chamber 

143 


960 

20-100 

15 

A 

140 

Large chamber; 90 F; wind 



1,100 

20-100 

10 

A 

140 

speed without effect 

104e 

Rat 

(750) 

10 

30 

N 

10 

Low-flow chamber 

37, 44a 


<1,200 

30 

15 

A 

34 

Static chamber 

143 


860 

20-100 

10 and 15 

A 

84 

Large chamber; OOF; wind 

104e 







speed without effect 


Guinea pig 

(2,500) 

10 

30 

N 

18 

Low-flow chamber 

37, 44a 


(1,500-3,000) 

30 

15 

A 

36 

Static chamber 

143 

Rabbit 

(1,000-3,000) 

10 

30 

N 

5 

Low-flow chamber 

37, 44a 


900 

30 

15 

A 

66 

Low-flow chamber; 90 F 

71 


(1,000) 

30 

15 

A 

18 

Low-flow chamber; 73 + F 

71 


(>4,000) 

30 

15 

A 

15 

Static chamber 

143 


900 

20-100 

15 

A 

84 

Large chamber; OOF; wind 

104e 


1,100 

20-100 

10 

A 

84 

speed without effect 



910 

360 

15 

A 

54 

Low-flow chamber; 90 F 

71 

Cat 

(400) 

10 

10-30 

N 

12 

Low-flow chamber 

37, 44a 

Dog 

(800) 

10 

10-30 

N 

14 

Low-flow chamber 

37, 44a 

Goat 

(1,500-3,000) 

30 

15 

A 

9 

Static chamber 

143 

Monkey 

(1,500) 

10 

15 

N 

6 

Low-flow chamber 

37 


flow rate, temperature, use of an anesthetic, and 
variable delayed deaths due to secondary infections. 

Wind speed or flow rate is only of marked im- 
portance for toxicity when aerosol is present. 

HNS when present in part as fine drops is much more 
toxic at high flow rates than at low flow rates.^^’^^® 
At high flows a greater liquid dose is deposited on the 
skin, from which it may be absorbed after exposure 
both directly and indirectly as a result of licking and 
inhalation of vapor. 

A number of data are available on the toxicities of 
the nitrogen mustards to animals exposed totally, by 
inhalation only, and by body only.^^’^^^-^'^'* In the 
case of mice totally exposed to HNS, the absorption 
of the agent from the body surface compares in im- 
portance with that directly inhaled. It is doubtful, 
however, that casualties among troops in the field 
would be produced by the systemic effects of nitro- 
gen mustard absorbed through the skin except when 
the exposures are already more than sufficient to 
produce vesicant effects of incapacitating sever- 

ity.104.lll 

Relatively high concentrations of the nitrogen 
mustards produce symptoms of irritation during ex- 
posure but lower concentrations 


are without immediate effect. Symptoms then 
develop only after a latency of one to several hours 
and the most conspicuous pathological changes ap- 
pear in the eyes and respiratory tract.®'* '^^’®^’’^^ 

Death in lethally dosed animals is usually delayed 
for one day to two or more weeks, depending on 
dosage. Detailed pathological studies have been 
made 77,78,81,85,121,139,140,141,143 

Data on the toxicities and pathological actions of 
nitrogen mustards administered percutaneously, 
orally, and by injection are presented in Chapter 22. 
From the practical point of view it may be noted that 
production of casualties from the drinking of con- 
taminated water could easily occur. The available 
chemical tests are, however, sufficiently sensitive to 
reveal potentially dangerous concentrations of the;, 
nitrogen mustards and their toxic products of partial 
hydrolysis (see also Chapter 34). 

6.4.3 Vesicant Action‘d 

The nitrogen mustards both as liquids and as 
vapors are potent vesicants. They are effective both 
on bare skin and through clothing. Vesicant action 

No attempt is here made to duplicate material presented 
in Chapter 23. 


SECRET 


TOXICOLOGY 


71 


Table 7. Toxicity of HN2. 
given in parentheses. 

The animals 

were totally exposed. L(C 05 o’s that 

are estimated very approximately are 

Species 

LiCtho 

(mg min/m^) 

Exposure 

time 

(min) 

Observation 

period 

(days) 

Analytical 

(A) 

or 

nominal 

(N) 

cone. 

Number 

of 

animals 

Notes 

Reference 

Mouse 

5,100 

2 

10 

N 

200 

Low-flow chamber 

77 


(6,000) 

2 

25 + 

A 

40 

Static chamber 

121 


(2,000-6,000) 

5 

25 + 

A 

40 

Static chamber 

121 


2,600 

10 

15 

A 

138 

Low-flow chamber 

29, 44b 


5,600 

10 

10 

N 

240 

Low-flow chamber 

77 


(2,000-7,000) 

10 

10 

N 

40 

Static chamber 

177b 


(2,000-6,000) 

10 

25 + 

A 

30 

Static chamber 

121 


(2,000) 

20 

25 + 

A 

40 

Static chamber 

121 


5,700 

30 

10 

N 

160 

Low-flow chamber 

77 


(1,500) 

30 

25 + 

A 

50 

Static chamber 

121 


(3,000-4,000) 

60-120 

? 

A 

36 

Low-flow chamber 

131 


(4,000-5,000) 

240-450 

? 

A 

54 

Low-flow chamber 

131 

Rat 

(600-1,200) 

2 

18 

A 

24 

Static chamber 

121 


(1,500) 

5‘"* 

<10 

A 

40 

Static chamber 

121 


<4,400 

10 

15 

X 

12 

Low-flow chamber 

44a 


(< 2,000) 

10 

<10 

A 

30 

Static chamber 

121 


(1,750) 

10 

10(?) 

N 

24 

Static chamber 

177b 


(< 1,800) 

20 

<10 

A 

30 

Static chamber 

121 


(1,000-3,000) 

30 

<10 

A 

30 

Static chamber 

121 


(2,000-3,000) 

60-120 

? 

A 

26 

Low-flow chamber 

131 


(2,000) 

120-360 

14 

A 

56 

Low-flow chamber 

131 


(2,000-4,000) 

240-450 

? 

A 

38 

Low-flow chanber 

131 


(2,000-3,000) 

240-510 

14 

A 

40 

Low-flow chamber 

131 

Guinea pig 

(>1,200) 

2 

? 

A 

24 

Static chamber 

121 


(3,000) 

5 

19 

A 

24 

Static chamber 

121 


(5,500) 

10 

15 

N 

12 

Low-flow chamber 

44a 


(3,500-7,000) 

10 

10(?) 

N 

16 

Static chamber 

177b 


(3,000-6,000) 

10 

5 

A 

20 

Static chamber 

121 


(4,000-8,000) 

20 

19 

A 

30 

Static chamber 

121 


(3,000-6,000) 

30 

7 

A 

30 

Static chamber 

121 


(>3,800) 

60-120 

? 

A 

8 

Low-flow chamber 

131 


(2,500-5,000) 

240-450 

? 

A 

14 

Low-flow chamber 

131 

Rabbit 

(>1,200) 

2 

25 

A 

24 

Static chamber 

121 


(1,000-3,500) 

5 

26 

A 

24 

Static chamber 

121 


(4,400) 

10 

15 

N 

4 

Low-flow chamber 

44a 


(7,000-14,000) 

10 

10(?) 

N 

12 

Static chamber 

177b 


(3,000) 

10 

15 

A 

19 

Static chamber 

121 


(2,000-8,000) 

20 

28 

A 

30 

Static chamber 

121 


(3,000-6,000) 

30 

26 

A 

29 

Static chamber 

121 

Cat 

<1,400 

10 

10-30 

N 

8 

Low-flow chamber 

44a 

Dog 

(2,000) 

10 

10-30 

N 

4 

Low-flow chamber 

44a 

Goat 

(1,000) 

2 

13 

A 

8 

Static chamber 

121 


(<800) 

5 

22 

A 

8 

Static chamber 

121 


(< 1,700) 

10 

? 

A 

6 

Static chamber 

121 


( <2,000) 

20 

? 

A 

8 

Static chamber 

121 


(1,000-2,000) 

30 

? 

A 

10 

Static chamber 

121 


through clothing is of more practical importance 
than action on bare skin because usually most of the 
body surface, including the areas that are at the 
same time the most sensitive and the most critical 
for incapacitation, is clothed. In addition to vesi- 
cancy through unimpregnated clothing, the degree 
of protection offered by chloramide-impregnated 


clothing and clothing containing activated carbon 
requires consideration. 

A further differentiation must be made between 
situations in which the skin is relatively cool and dry 
and situations in which it is hot and moist. As in the 
case of H, high temperatures and humidities and 
physical exercise augment the sensitivity of men to 


SECRET 


72 


NITROGEN MUSTARDS 


Table 8. Toxicity of HNS. The animals were totally exposed. L(C05o’s that are estimated very approximately are 
given in parentheses. 

Analytical 

(A) 

or 


Species 

LiCtho 
(mg min/m^) 

Exposure 

time 

(min) 

Observation 

period 

(days) 

nominal 

(N) 

cone. 

Number 

of 

animals 

Notes 

Reference 

Mouse 

(1,700) 

<2 

18 

A 

132 

Fine aerosol 

144 


500-600 

10 

14-15 

A 

58 

Aerosol-free vapor 

104a 


590 

10 

15 

A 

230 

Low-flow chamber 

37 


300 

10 

15 

A 

60 

High-flow chamber; aero- 








sol present 

37 


(165) 

10 

15 

A 

20 

Vapor; wind tunnel; 95 F 

37 


1,700 

10 

10 

N 

160 

Low-flow chamber 

78 


570 

10-100 

15 

A 

139 

Vapor, 90 F, 85% humidity 

104c 

Rat 

(800) 

0.25-2 

20 

A 

104 

Fine aerosol 

144 


1,700 

10 

15 

N 

28 

Low-flow chamber 

54 


(800-1,500) 

10 

15 

A 

18 

Low-flow chamber 

37 


(< 1,000) 

30 

? 

A 

50 

Static chamber; 85 F 

139 


670 

10-100 

15 

A 

69 

Vapor, 90 F, 85% humidity 

104c 

Guinea pig 

>2,300 

10 

? 

N 

10 

Low-flow chamber 

37 


>1,000 

30 

? 

A 

45 

Static chamber; 85 F 

139 

Rabbit 

(585) 

3-15 

15 

A 

12 

Vapor; wind tunnel; 5.5 mph; 








95 F 

37 


(1,000-3,000) 

10 

10 

N 

11 

Low-flow chamber 

37 


(500) 

10-18 

15 

A 

8 

Low-flow chamber; vapor 








only; 100 F 

37 


(830) 

18-50 

15 

A 

30 

Low-flow chamber; vapor 








only; 72 F 

37 


(>1,000) 

30 

? 

A 

31 

Static chamber; 85 F 

139 


635 

10-100 

15 

A 

70 

Vapor; 90 F, 85% humidity 

104c 


550 + 

long 

15 

A 

60 + 

Field tests 

65 

Cat 

(400-1,000) 

10 

? 

A 

32 

Low-flow chamber 

37 

Dog 

(400-1,500) 

10 

? 

A 

36 

Low-flow chamber 

37 


<1,350 

30 

? 

? 

? 

Low-flow chamber 

187 

Goat 

(500-1,000) 

30 

? 

A 

18 

Static chamber; 85 F 

139 


the vesicant effects of the nitrogen mustards (see 
Chapter 23). 

So far as is known the time course of development 
of injury and incapacitation due to skin injury ap- 
pears to be comparable. for H and the nitrogen mus- 
tards (see Chapters 5 and 23). Some evidence exists 
that nitrogen mustard burns are shallower than H 
burns and heal more quickly.®® On the other 
hand nitrogen mustard burns have been referred to 
as more tender and painful than H burns.®® How- 
ever, a sufficiently complete and realistic determina- 
tion by means of performance tests of the relative 
extent and duration of incapacitation produced by 
lesions due to H, HNl, HN2, and HN3 remains to be 
made. Thus at present evaluations must be based prin- 
cipally on lesion-producing effectiveness rather than 
on the more pertinent criterion of casualty-produc- 
ing effectiveness. Furthermore there is no informa- 
tion as to the effects of large dosages of nitrogen 
mustard vapors upon masked troops. In the case of 
H it is known that severe exposures under tropical 


conditions produce incapacitation within one hour 
of exposure due to temporarily incapacitating nausea 
and vomiting followed rapidly by the development 
of very severe cutaneous injury.^^® No evidences of 
systemic injury have been apparent in any of the 
man-chamber trials with HNl and HN3 at the rela- 
tively low dosages that have been utilized.^®'^*'’®’®’^^ 

Vesicancy of the Liquids 

1. Cool and temperate conditions. For the produc- 
tion of lesions on bare skin when free evaporation is 
permitted and decontamination is not practiced, 
the order of vesicant potency is H > HN3 > HN2 
> HNl. The relative weights of the small liquid 
drops required to produce blisters at 50 per cent of 
the sites of application are:^®’'^'*®’®’^*^’*’^’®^-^®^ 

H 1 

HN3 2-4 

HN2 4-8 

HNl >8 


SECRET 


TOXICOLOGY 


73 


The agents fall in the same relative order when 
evaluated by more realistic tests in which the sizes 
of the lesions produced by large drops are com- 
paredd'^*'^^’^®^ None of the other nitrogen mustards 
and related compounds are as vesicant as HN2 or, 
probably, as vesicant as HNl (see Table l). 41 . 148,191 

When effective decontamination is practiced 1 to 
5 minutes after contamination, H produces markedly 
greater lesions than HN3d®^ The positions of HNl 
and HN2 are not known with certainty; HN2 may 
be only slightly inferior to H and HNl somewhat 
inferior to HN2d^® Antivesicant ointments (i.e.. 
United States M5 and British A.G. No. 6) available 
to Allied troops during World War II do not destroy 
the nitrogen mustards as they do H, but their bases 
are good solvents for the nitrogen mustards. The 
latter are effectively decontaminated by solvent and 
mechanical action when large amounts of ointment 
are applied and then wiped If the oint- 

ment is left in place on the skin, the dissolved but 
undestroyed nitrogen mustard may slowly exert its 
vesicant action and the lesions produced by small 
doses of H and HN3 become comparable in sever- 
ity 34,44f.g Dilute acids also exert a solvent action on 
the nitrogen mustards, and such oxidizing agents as 
permanganate in aqueous solution may be utilized 
as decontaminants. In addition, some chloramides 
not in general use by the Allies during World War II 
do destroy nitrogen mustard readily. Notable among 
these are S-436, 

NCI 2 NCI 2 

I 1 

CeHs— C=N— C=N— C=N 
1 ^1 

and the German Decontaminant 40, 

0 Cl O Cl 0 Cl 

II I II I II I 

C— N— C— N— C— N 
I ^1 

(see Chapter 24). 

Through one or two layers of unimpregnated cloth 
the order of lesion-producing potency is H > HN2 
> HNl HN3.^^’^^®'^^® The order found for bare 
skin is modified because of the importance of vapor 
pressure for the transport of the agent through the 
cloth and to the underlying skin. 

Through cloth impregnated with CC-2 the nitro- 
gen mustards gain in effectiveness relative to H be- 
cause of the comparative ineffectiveness of CC-2 as 
a decontaminant for nitrogen mustard. Laboratory 


data insufficient to permit a conclusive estimate sug- 
gest the following order of potency: HN2 > H 
> HNl > HN3.®^ Realistic trials under field con- 
ditions are lacking. 

2. Hot and humid conditions. The scanty avail- 
able data do not permit an evaluation of the relative 
potencies of the three liquids under tropical condi- 
tions. The lesions produced by small doses of the 
liquids on resting men and on men exercised to the 
point of sweating under temperate conditions suggest 
that the differences which would be observed among 
the agents if they were tested under severe tropical 
conditions might be less pronounced than those 
which have been obtained on relatively cool, dry 
skin.^j 

Vesicancy of the Vapors 

1. Laboratory evaluation of potency. Laboratory 
data which relate to the production of lesions on 
limited areas of the skin of the forearms of men not 
acclimated to hot summer weather and exposed un- 
der relatively moderate ambient conditions of tem- 
perature and humidity demonstrate that on a dosage 
basis HN3 is equal to or slightly more effective than 
H, that HN2 is definitely inferior to both H and 
HN3, and that HNl is greatly inferior to each of the 
three other agents (Tables 9 and 10). 


Table 9. Vapor train tests of the vesicant potencies of 
the vapors of H, HNl, HN2, and HNS.^* 

The subjects were at rest. T = 80 F. 


Agent 

Analytical Ct (mg min/m^) 
for 50 per cent responses 
Erythemas Blisters 

Relative 

dosage* 

H 

<430 2,500 

1 

HNl 

2,700+ >21,000 

>8 

HN2 

1,200 ± 5,800 

2 + 

HN3 

400 ± 1,800 

0.7 + 

* Reciprocal of vesicant potency. 

Table 10. Vapor cup tests of the vesicant potencies of 

the vapors of H, HNl, and HN3.®® 

The subjects were at rest. T = 72- 

-73 F. 

Agent 

Estimated median vesicating 
dosage in mg min/m^ 

(t = 5-60 min) 

Relative 

dosage* 

H 

3,500 

1 

HNl 

18,000 

5 + 

HN3 

3,700 

1.1 


* Reciprocal of vesicant potency. 


These relationships for H, HNl, and HN3 are con- 
firmed by arm-chamber studies at high temperatures 


SECRET 


74 NITROGEN MUSTARDS 


Table 

11. Basic man-chamber tests with H and nitrogen mustard vapors: 

United States Army data.^”^’^-®'*^-® 


7" = 90 F. Relative humidity = 85 per cent. All subjects wore gas masks, shoes, and socks. 



Additional 


Vapor 

Exposure 


Genital 

clothing 

N umber 

dosage 

time 


Season 

protection 

and protection 

of men 

(mg min/nU) 

(min) 

Effects 

Summer 

CC-2 impregnated 


H 





shorts 

None 

3 

106 

10 

Moderate erythema of neck. 







back, and legs. 

Summer 

CC-2 impregnated 







shorts 

None 

6 

200 

20 + 

Severe erythema of neck. 







thorax, abdomen, and legs; 
some delayed superficial 
vesication. 




HNl 




Summer 

CC-2 impregnated 







shorts 

None 

3 

107 

11 

No effects. 

Summer 

CC-2 impregnated 







shorts 

None 

3 

211 

22 

No effects. 

Summer 

CC-2 impregnated 







shorts 

None 

3 

285 

30 

Questionable erythema of 







neck. 

Summer 

CC-2 impregnated 







shorts 

None 

3 

520 

34 

Mild erythema of neck; | 







mild erythema of back. 

Summer 

CC-2 impregnated 







shorts 

None 

3 

689 

41 

Mild erythema of neck and 







body. 

Summer 

CC-2 impregnated 







shorts 

None 

3 

940 

44 

1 moderate and f moderate 







erythema of upper trunk. 

Summer 

CC-2 impregnated 







shorts 

None 

3 

1,030 

29 

§ moderate erythema of axil- 







lary folds; 1 mild ery- 
thema of upper back and 
neck. 




HNS* 




Winter or 

Unimpregnated 






early spring 

shorts 

None 

2 

90 

15 

No genital injuries: minimal 

Winter or 

Carbon-contain- 





erythema over exposed 

early spring 

ing shorts 

None 

2 

90 

15 

> skin, marked over neck, 

back, and anterior axillary 
folds. 

Winter or 

Carbon-contain- 






early spring 

ing shorts 

None 

3 

150 

25 

Generalized moderate ery- 







thema at 20 hours which 
had reached its maximum 







and begun to decrease by 
96 hours. Erythema most 
pronounced on neck, back, 
and anterior axillary folds. 

Winter or 

Carbon-contain- 






early spring 

ing shorts 

None 

4 

200 

? 

1 slight and j moderate ery- 







thema of trunk and neck; 
f minimal erythema on 
legs. 

Winter or 

Carbon-contain- 






early spring 

ing shorts 

None 

3 

250 

? 

Slight erythema of trunk. 







moderate erythema of 



1 




neck; f minimal erythema 
of legs. 


* Wind speed in the chamber seemed to be without effect and has been disregarded in compiling this table. 


SECRET 


TOXICOLOGY 


75 




Table 1 

1 {Continued). 



Season 

Genital 

protection 

Additional 
clothing 
and protection 

Number 
of men 

Vapor 
dosage 
(mg min/m^) 

Exposure 

time 

(min) 

Effects 

Winter or 
early spring 

Carbon-contain- 
ing shorts 

None 

HNS* 

8 

300 

? 

1 slight, f moderate, and f 

Winter or 
early spring 

Carbon-contain- 
ing shorts 

None 

4 

350 

? 

marked erythema of trunk ; 
more pronounced ery- 
thema of neck; minimal 
erythema of legs. 

Areas of vesication on trunk 

Winter or 

Carbon- contain- 

N onimpregnated 

4 

350 

? 

and neck; marked ery- 
thema with edema and 
moist desquamation of 
ears and preauricular 
areas; slight erythema of 
scalp; minimal erythema 
of legs. 

1 slight erythema of neck; 

early spring 

ing shorts 

2-piece herring- 
bone twill suit, 

M5 ointment on 
neck. 




I vesication of neck. 


* Wind speed in the chamber seemed to be without effect and has been disregarded in compiling this table. 


and humidities with the exception that, when tests 
were made with sweating observers acclimated to 
hot summer weather, HNl assumed a much more 
favorable relative position, requiring only 1.2 to 
1.6 times the dosage of H to produce equivalent 
lesions.^®® The effectiveness of H, HNl, and HNS 
vapors in these tests was little affected by the inter- 
position of a layer of unimpregnated cloth. 

2. Man-chamber evaluation of 'potency. The only 
available man-chamber tests of the effects of nitro- 
gen mustard vapors on observers wearing no cloth- 
ing or unimpregnated clothing are summarized to- 
gether with representative data for H in Tables 11 
and These data relate to a chamber 

temperature of 90 F and relative humidities of 65 
and 85 per cent, and to the production of injuries 
corresponding only to relatively mild partial dis- 
ability. 

Although the two groups of data show some dis- 
crepancies, it seems reasonable to conclude that, in 
warm or hot weather and against troops provided 
with gas masks but not with protective clothing, 
HNS vapor may approach H vapor in potency as a 
casualty-producing agent, particularly when the 
genital region is unprotected. HNl vapor, except 
possibly on freely sweating men acclimated to hot 
weather, appears to be definitely inferior to H and 
HNS. The laboratory findings (see the preceding 
section) suggest that HN 1 vapor would be markedly 
inferior under cool or temperate conditions. 


S. Evaluation of protective clothing. The merits 
and limitations of the CC-2 impregnated and the 
carbon-containing types of protective clothing are 
reviewed in Chapters 26 to SO. In brief, the data 
109,111,113 reveal that CC-2 impregnated clothing offers 
excellent protection against H, considerable pro- 
tection against HNS, and relatively little protection 
against HNl. Thus, in the tropics against troops 
protected by this clothing, HNl vapor may be a 
more potent casualty-producing agent than H. The 
relative positions of H and HNS are not known but 
may not be important because of the high degree of 
the protection afforded against both agents. 

The best experimental types of carbon clothing 
now available offer protection against such large 
dosages of H, HNl, and HNS (presumably also 
HN2) that differences beWeen the dosages of the 
agents required to “break” this clothing become of 
minor consequence. 

4. Protection afforded by ointment. Prophylactic 
use of S-SSO ointment, and presumably other oint- 
ments containing the chloramides available to Allied 
troops during World War II, offer little protection 
to skin exposed to nitrogen mustard vapor. 

6.4.4 Eye-Injurant Action 

Numerous observations on the effect of the nitro- 
gen mustards on human and animal eyes demonstrate 
that HNl, HN2, and HNS are eye-injurants more 
insidious than H and more or less comparable with it 


SECRET 


76 


NITROGEN MUSTARDS 


Table 12. Basic man-chamber tests with H and nitrogen mustard vapors; United States 
Naval Research Laboratory data.^^®-^^^ 

T = 90 F. Relative humidity = 65 per cent. Exposure time = 60 minutes. All sub- 
jects wore gas masks, unimpregnaied outer and under clothing, caps, shoes, and socks. The 
maximum lesions sustained on various parts of the body over a period of approximately a 
week were graded according to the following numerical scale: 

0 = No reaction. 

1 = Mild erythema. 

2 = Moderate erythema. 

3 = Intense erythema. 

4 = a. Erythema with edema. 

b. Maceration of axillary skin. 

c. Dry scaling of scrotum. 

5 = a. Vesicle. 

b. Numerous pinpoint vesicles. 

c. Crusting or ulceration of scrotum or axilla. 


Season 

N umber 
of men 

Vapor 
dosage 
(mg min/m^) 

Neck 

Severity of injury 

Scrotum 

Rest of 
body 

No. of 
crusted or 
ulcerated 
scrotal 
lesions 

March 

6 

50 

H 

0.3 

0.0 

0.1 


July 

5 

50 

1.2 

0.2 

0.5 


March 

6 

100 

1.2 

1.2 

0.7 


July 

5 

100 

1.6 

0.8 

0.9 


April 

10 

150 

2.0 

0.3 

0.7 


July 

6 

150 

3.0 

2.2 

2.1 


April 

10 

200 

2.2 

2.1 

1.2 


July 

6 

200 

4.0 

3.2 

2.4 


April 

15 

250 

2.4 

3.2 

1.6 


July 

6 

250 

4.2 

3.7 

2.8 


November 

6 

300 

3.3 

0.0* 

2.4 


March 

5 

300 

3.4 

0.0* 

2.9 


August 

10 

100 

HNl 

1.3 

1.2 

0.3 

0/10 

August 

10 

200 

3.4 

1.4 

1.2 

0/10 

August 

10 

300 

3.3 

4.6 

1.7 

7/10 

January 

8 

300 

1.9 

0.6 

0.3 

0/10 

January 

4 

450 

1.8 

1.5 

0.6 

0/10 

January 

6 

700 

2.2 

4.0 

0.6 

4/6 

September 

8 

50 

HNS 

1.8 

0.5 

0.2 

0/8 

September 

8 

100 

3.0 

1.9 

0.8 

1/8 

September 

8 

150 

4.0 

4.0 

1.8 

6/8 

August 

8 

150 

2.0 

0.0* 

0.2 • 

0/8* 

F'ebruary 

6 

150 

1.5 

0.3 

0.7 

0/6 

February 

6 

250 

2.5 

1.5 

0.8 

0/6 

. February 

8 

350 

4.9 

3.6 

1.7 

6/8 


* Subjects wore CC-2 impregnated shorts. 


in potency S, 44c, d.h, 45. 56,57, 63, 64, 65,66,69, 70,71, si, 84, 85,88,101,104b, 
c, 106a, 112, 115, 118, 123, 132, 133, 134, 138, 142, 150, 152, 156, 174, 175, 180, 184 Pj-q- 

pyl-6ts(j(3-chloroethyl) amine and isopropyl-6ts(iS-chlo- 
roethyl)amine appear to be somewhat less potent.'^'**'’ 

81,134 

Effects of the Vapors in Small Dosages on 
Human Eyes 

The results of ob.server tests with H, HNl, HN2, 
and HNS as vapors demonstrate that all four agents 


are roughly comparable on a potency (dosage) basis 
in eye-injurant action. Provisionally it would appear 
that HN2 and HNS may be somewhat more potent 
than H, and HNl somewhat less potent, but the dif- 
ferences cannot be considered to have been estab- 
lished with significance (see the following section for 
animal data). The importance of the human eye 
data merits their more detailed review as follows. 

1. H. Critical summary and review 112,113 
four available sets of data lova, 119, 147a, i96a suggest that 


SECRET 


TOXICOLOGY 


77 


50 mg min/m^ {t < S hours) is the maximum dosage 
to which unmasked personnel may be exposed with- 
out danger of significant eye damage, and that 
100 mg min/m^ (^ = 6 minutes to 7 hours) is the 
threshold dosage for production of partial disability. 
Extrapolation from the data leads to the estimate 
that for offensive purposes 200 mg min/m^ (t = 
6 minutes to 7 hours) would suffice to produce in- 
capacitating conjunctivitis and blepharospasm, with 
lacrimation, photophobia, and soreness, and perhaps 
with some corneal damage, in the majority of men 
for a period of 2 to 7 days, beginning 3 to 12 hours 
after exposure. H vapor is somewhat less effective at 
very short (i.e., 1 to 2 minute) and very long ex- 
posure times. 

2. HN1.^'‘2 A dosage of 90 mg min/m^ is believed 
to represent the beginning of the human casualty 
zone, on the basis of tests in which one eye of each of 
21 observers was exposed in a respirator facepiece to 
5 1/min of HNl vapor (Ct = 37 to 90, ^ = 5 to 67 
minutes). There was no serious change of vision ex- 
cept for three men, exposed to dosages of 41, 56, and 
90 respectively, who did not think they could shoot 
a rifle for 48 hours. Only one of three men exposed to 
a dosage of 90 was a “casualty” in this sense. There 
was an average delay of 12 hours in the development 
of symptoms, which included gritty feeling, lacrima- 
tion, photophobia, blepharospasm, headache, blurred 
vision, conjunctival hyperemia, corneal flecks, epi- 
thelial bedewing, and punctate staining with flu- 
orescein. Minor symptoms persisted in one case for 
as long as 24 days. The conclusions of the report are 
transcribed verbatim as follows : 

a. A dosage of HNl of 90 mg min/m^ is prob- 
ably the beginning of the human casualty 
zone, but with ocular idiosyncrasy casual- 
ties can occur at lesser dosages. 

b. The average interval between exposure and 
onset of symptoms was 13 hours. 

c. The most common complaint was “gritty” 
foreign body sensation in the eye. 

d. The most common lesion was flecks of the 
corneal epithelial surface which disappeared 
spontaneously in 1 to 15 days. Conjunctival 
hyperemia occurred almost as frequently. 

e. The most annoying symptom was pain in 
and behind the eyeball. 

f. Other complaints were lacrimation, photo- 
phobia, and blurred vision, although there 


was never any reduction in visual acuity or 
accommodation. 

g. Blepharospasm occurred in only two ob- 
servers and myosis in only one. 

h. So far as can be judged from the results ob- 
tained, the dosage (Ct) of HNl vapor is a 
sufficient index to the degree of damage 
anticipated, even though the exposure time 
be varied from 5 to 60 minutes (but see 
below) . 

3. HN2.^2^ Dosages of 40 to 55 mg min/m^ (t = 
0.5 and 10 minutes, respectively) are believed to 
represent the lowest limits of exposure necessary to 
produce “disablement” — i.e., certain cases would 
call for medical aid and, to an extent depending on 
transport and medical facilities, would be unable to 
take part in operations for a minimal period of 1 to 
2 weeks. This conclusion was based on experiments 
in which an unstated number of men wearing oro- 
nasal masks were exposed in a man-chamber to 
dosages of 10 to 55 mg min/m^. The performance of 
additional human experiments at higher dosages was 
considered to involve an unreasonable risk. There 
were no subjective symptoms during exposure. From 
8 to 15 minutes after exposure lacrimation and a feel- 
ing of grittiness under the lids developed. After 6 to 
10 hours the following symptoms had set in: lacri- 
mation, photophobia, blepharospasm, and pain in 
the eyeball severe enough to prevent sleep. At 24 
hours the symptoms were similar but the pain had 
become less severe. There was pupillary constriction, 
conjunctival congestion, deep ciliary congestion, and 
threshold edema of the corneal epithelium, but no 
staining with fluorescein. The condition was resistant 
to mydriasis with 1 per cent homatropine but pupil- 
lary dilatation and relief of blepharospasm was 
achieved by two applications of 1 per cent atropine. 
The observers gave their opinion that their efficiency 
as soldiers would have been seriously impaired from 
6 to 10 hours onward. The duration of the symptoms 
was not stated. The report recommends that a dosage 
of 70 mg min/m^ be aimed at as a minimum for of- 
fensive purposes. 

4. HN3.^®^''’‘' Of four observers exposed to a dosage 
of 20 mg min/m^ {t = ?), none experienced any sub- 
jective symptoms but all showed moderate conjunc- 
tival injection. Their corneas were grossly normal 
but examination with the slit lamp revealed moderate 
to marked epithelial edema. Of three observers ex- 
posed to a dosage of 42 mg min/m^ {t = 7 minutes). 


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78 


NITROGEN MUSTARDS 


Table 13. Eye damage produced in rabbits by the vapors of H, HNl, and 

Eight animals were exposed to each agent at each dosage. The eye damage was graded according to an 
arbitrary numerical system^®®®^ which took account of changes in the iris, cornea, conjunctivas, and lids. The 
analytical dosages of the agents were determined by methods adequate to integrate low concentrations 
over long times. 

Exposure time 
(min) 

H 

Dosage 
(mg min/m®) 

Eye 

damage 

HN3 

Dosage 
(mg min/m®) 

Eye 

damage 

HNl 

Dosage 
(mg min/m®) 

Eye 

damage 

2 

440 

20 

353 

21 

485 

30 


384 

19 



439 

29 

10 

330 

29 

410 

23 

650 

15 


370 

24 



389 

12 

60 

420 

23 

418 

25 

435 

12 


434 

24 



460 

10 

200 

420 

17 





240 

347 

21 

411 

16 

530 

11 






466 

10 

360 

330 

13 






all developed lacrimation, photophobia, and a feeling 
of grittiness in the eye. They exhibited marked con- 
junctival injection. Their corneas were grossly nor- 
mal and did not stain with fluorescein but examina- 
tion with the slit lamp revealed epithelial edema and 
slight infiltration of the anterior stroma. One de- 
veloped moderate edema of the lids. All three were 
improving both subjectively and objectively on the 
fourth day after exposure. On the basis of the brief 
available description it would appear that HNS pro- 
duced effects comparable to those found for H in one 
investigation and more severe than those found 
for H in two other investigations. 

The clinical reports of plant accidents indicate that 
the development of eye symptoms due to the vapors 
of HNl and HNS were delayed for several hours.®®’^^'‘ 
The same delay was experienced by some workers ex- 
posed to HN2 vapor, but others developed, eye irri- 
tation, lacrimation, and photophobia immediately 
after exposure. 

Effects of Vapors on Animal Eyes 

Although the animal (i.e., rabbit) eye is consider- 
ably more resistant to H and nitrogen mustard va- 
pors than is the human it may be assumed 

that the relative potencies of the different agents can 
be determined in animal tests. 

The most satisfactory available set of comparative 
data is summarized in Table I3.44h.i06a results 
suggest that the rabbit is approximately as suscep- 
tible to HNS as to H. HNl is probably more potent 
than H and HNS at very short exposures (i.e., 2 min- 
utes) but significantly less potent for exposure times 
of 10 to 240 minutes. The results of less rigorously 


controlled earlier work with dogs exposed for 10 min- 
utes suggest that HNl, HN2, and HNS produce 
threshold corneal damage at somewhat lower dosages 
than H; that at low dosages HNS is the most potent 
eye-damaging agent, followed by HNl, HN2, and H; 
and that at higher (but still moderate) dosages the 
differences among the four compounds are less con- 
spicuous.'^^'^ 

In tests with relatively large vapor dosages which 
produced severe ocular injury, it was found that the 
dosages required to produce equally severe super- 
ficial corneal and conjunctival injury were about the 
same for each of the three nitrogen mustards.^^*" With 
equally severe injury to the superficial corneal tis- 
sues, however, the damage to the deeper tissues (i.e., 
iris and ciliary body) was much the greatest with 
HN2, intermediate with HNS, and least with PINl 
and The severity of the deep ocular effects pro- 
duced by HN2 make it a particularly dangerous 
agent from the standpoint of severe and permanent 
eye injury. 

The results of additional studies on the effects of 
nitrogen mustard vapors on animal eyes are to be 
found in the following references, some of which con- 
tain more or less complete histopathological analy- 

ggg 44d ,45 ,57a ,c ,65 , 70 , 71 , 84 , 85 , 123 ,138 , 142 

The clinical and pathological studies with HN2 
have been reviewed in detail.®'"^ 

Liquid Contamination of the Eye 

Tests on animal eyes with small liquid drops (i.e., 
0.5t mg) of H, HNl, HN2, and HNS demonstrate 
that all the agents produce such severe burns, fre- 
quently with permanent loss of sight, that any differ- 


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RESULTS OF FIELD TRIALS 


79 


ences in potency which may exist are relatively un- 
important to an evaluation of their relative merits as 
offensive agents. The observations 
tend to emphasize the similarity of the lesions pro- 
duced by H and HNS and the more severe character 
of the injury that HN2 produces in the deeper struc- 
tures of the eye. 

The effects of small droplets, and in the wind tun- 
nel of sprays consisting of fine droplets and vapor, 
have also been studied in animal experiments in 
order to assess the relative effectiveness of the agents 
in the initial clouds produced by bursting muni- 
tions.^2^-^^®'^®2 The results indicate that HNS may be 
slightly less damaging, and HN2 slightly more dam- 
aging, than H. In any event the differences are not 
marked. 

Decontamination and Treatment 

Decontamination can be effected practically only 
by prompt lavage of eyes contaminated with the 
agents in the liquid form. There is some evidence that 
lavage is of less value with HNS than with H.^^® 
Prompt use of dithiocarbamates or of BAL ointment 
may be of limited value. 

The subject of treatment has been authoritatively 
reviewed. The susceptibility to infection of eyes in- 
jured by nitrogen mustard and the value of various 
types of chemotherapy have recently been investi- 
gated. 

6.5 RESULTS OF FIELD TRIALS 

Field trials with the nitrogen mustards have in- 
cluded tests of the vapor return from contaminated 
terrain and study of casualties in animals exposed to 
clouds of liquid drops and vapor produced by burst- 
ing munitions. No observer tests have been made to 
determine the vesicant effects of evolved vapor in the 
field or the hazard to traversal and occupation which 
is presented by the liquids on soil and vegetation. 

The results of the tests reviewed in Section 6.2.4 
attest to the excellent stability of HNS, the probably 
adequate but marginal stability of HNl, and the 
questionable stability of HN2. 

HNI, HN2, and HNS, as well as H, dispersed from 
explosive munitions as clouds of liquid drops and 
vapor can produce profound eye damage and serious, 
often fatal, respiratory injury in unprotected ani- 
mals exposed on open terrain (see references cited in 
Section 6.2.4). However, such trials may have only 
limited bearing on the general utility of the agents 
in warfare. 


Evolution of Vapor from Contaminated Terrain 

Results of field trials (see Table 14) conducted dur- 
ing warm weather at Bushnell, Florida, are avail- 
able.®^-®® The tests included both annulus trials and 
trials with single, statically exploded M47A2 bombs. 
They lead to the following tentative conclusions. 

1. When terrain is similarly contaminated with 
HNS and Levinstein H, the vapor dosage of H 
evolved during the first few minutes is five to eight 
times as great as that of HNS, as would be predicted 
from the relative volatilities of the agents. With the 
passage of time the relative dosage of evolved HNS 
vapor becomes progressively greater until, after the 
lapse of sufficient time for the completion of the 
evaporation process, the total dosages of the two 
agents become approximately equivalent. The time 
interval after which the evolved dosage of HNS at- 
tains any specified fraction of the H dosage depends on 
the meteorological conditions and the size of the 
liquid drops with which the terrain is contaminated. 

2. In trials under seniitropical meteorological con- 
ditions with single, statically fired M47A2 bombs 
charged HNS or Levinstein H, the areas over which 
toxicologically significant dosages of HNS vapor 
were obtained within 4 hours amounted to substan- 
tial fractions of the areas over which equivalent 
dosages of H vapor were obtained (see Table 14). 

S. It is estimated ®® that in large-scale attacks un- 
der the semitropical conditions prevailing during the 
Florida trials the 4-hour vapor dosages obtained 
from equal expenditures of M47A2 bombs charged 
HNS or Levinstein H would be: 


4-hour vapor dosages, 


Meteorological conditions 

HNS as per cent of H 

Woods, clear day 

45 

Woods, clear night 

20 

Open, clear day 

65 


4. At the lower surface temperatures character- 
istic of cool or temperate weather, the times after 
contamination at which the evolved HNS vapor 
dosages would attain the above percentages of the 
H dosages would be greatly prolonged. 

5. Under semitropical meteorological conditions 
the persistencies of vapor evolution by HNS and 
Levinstein H are not markedly different. Both are, 
of course, much less than that of HT (see Chapter 5). 

6. HNS vapor evolved from contaminated terrain 
in the annulus and bomb trials was proved by bio- 
assay tests to be toxicologically effective. On the 
basis of the respiratory and ocular lesions produced 
in rabbits exposed at intervals up to more than 24 


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80 


NITROGEN MUSTARDS 


Table 14. Results of field trials with HNl, HNS, and H; single bomb tests. 


Agent and 
test 

Bomb 

Avg 
wind 
speed at 
2m (mph) 

Average 
ground 
temp (C) 

Avg temp 
gradient 

Torn — To.2m, 
in the open 

Area (artillery squares) within the contours for the 
stated dosages (Ct’s in mg min/m^) for 0 to 0 + 

4 hour sampling at a height of 12 inches. 

50 100 250 500 1,000 2,500 

HNl, test 4 

H, predicted 

M47A2 

4.4S 

Meadow, lapse conditions 
2S.81 -1.11 0.98 

0.61 

0.S2 

0.17 

0.09 


M47A2 

4.4S 

2S.81 

-1.11 

1.01 

0.59 

0.29 

0.17 

0.10 


H, observed 

M47A2 

4.S 

17.0 

-1.2 

0.81 

0.51 

0.22 

O.IS 

0.07 


HNl, test 6 

M47A2 

4.0 

2S.0 

+0.7 

1.72 

l.OS 

0.48 

0.27 

0.15 

0.06 

H, predicted 

M47A2 

4.0 

2S.0 

+0.7 

1.77 

l.OS 

0.51 

0.29 

0.17 

0.08 

H, observed 

M47A2 

4.41 

21.09 

+0.52 

2.18 

1.22 

0.55 

O.Sl 

0.17 


HNS, test 6 

M47A2 

S.S 

S5.2 

-1.1 

0.76 

0.50 

O.SO 

0.18 

0.11 

0.06 

H, predicted 

M47A2 

S.S 

S5.2 

-1.1 

1.S4 

0.79 

0.40 

0.2S 

0.14 

0.07 

H, observed 

M47A2 

4.8 

S2.8 

-1.S2 

0.77 

0.48 

0.25 

0.16 

0.10 

0.06 

H, observed 

M70 

4.2 

S6.2 

-2.24 

0.71 

0.45 

0.2S 

0.14 

0.09 

0.05 

HNS, test 4 

M47A2 

1.06 

Forest, lapse conditions 
29.S -1.05 0.57 

0.S5 

0.20 

O.IS 

0.09 

0.06 

H, predicted 

M47A2 

1.06 

29.S 

-1.05 

0.92 

0.59 

0.S5 

0.24 

0.16 

0.08 

H, observed 

M47A2 

0.9 

27.5 

-1.10 

1.10 

0.72 

0.41 

0.25 

0.16 

0.09 

H, observed 

M70 

0.5 

26.5 

-l.OS 

0.90 

0.67 

0.45 

0.S2 

0.22 

0.12 

H, observed 

M70 

0.9 

28.8 

-1.08 

0.45 

O.SO 

0.20 

0.14 

0.10 

0.07 

HNS, test 5 

M47A2 

0.5 

Forest, inversion conditions 
24.5 +0.S 1.18 

0.64 

0.24 

0.12 

0.08 

0.05 

H, predicted 

M47A2 

0.5 

24.5 

+0.S 

S.8S 

2.S8 

1.21 

0.71 

0.S8 

0.19 

H, observed 

M47A2 

0.6 

21.5 

-1.45 

1.16 

0.66 

0.S6 

0.2S 

O.IS 

0.06 

H, observed 

M47A2 

0.5 

19.5 

+ 1.76 

4.18 

2.78 

1.27 

0.76 

0.20 

0.08 

H, observed 

M70 

0.6 

25.5 

+0.80 

2.75 

2.02 

1.S8 

0.84 

0.47 

0.17 


hours after exposure, HNS vapor was significantly 
more potent than H vapor. 

7. When terrain is similarly contaminated with 
HNl and Levinstein H in the form of large drops in 
annulus trials conducted in the open in warm 
weather, the initial rate of vapor evolution was 
greater for HNl than for H, as would be predicted 
from the relative volatilities, and the 4-hour dosages 
of HNl were nearly twice those of H. 

8. In the available single-bomb trials in the open 
under semitropical meteorological conditions the 
4-hour dosages of HNl vapor were approximately 
equal to those obtained with H in similar tests (see 
Table 14). Approximately 90 per cent of the total 
evolved dosage of HNl vapor had been attained 
within this time. 

9. Analysis of the data indicates that the destruc- 
tion of HNl during the explosion or, subsequently, 
by inactivation on soil and foliage may have been as 
much as 30 per cent greater than the loss of H. Tak- 
ing these results in connection with those of British 
annulus trials which indicated 50 per cent de- 
struction of HN 1 on soil, it seems probable that large 
variations in per cent destruction may be expected, 
depending on the munition utilized and the char- 
acter of the terrain upon which the agent is deposited. 


Even greater variations might be expected in the 
case of HN2. 

10. HNl vapor evolved from contaminated ter- 
rain in the annulus and bomb trials was proved by 
bioassay tests to be toxicologically effective. In 
terms of the respiratory and ocular injuries produced 
in exposed rabbits, it was somewhat less effective on 
a dosage basis than HNS vapor under similar con- 
ditions. 

6.6 EVALUATION AS WAR GASES 

The instability of HN2 disqualifies it from serious 
consideration for use as a war gas. Isopropyl-6fs(i3- 
chloroe thy 1) amine is also disqualified because its 
somewhat inferior toxicological potencies are not 
counterbalanced by other advantageous properties. 
Thus only HNl and HNS remain as potential sub- 
stitute persistent agents for H. In Table 15 are sum- 
marized the properties of H, HNl, and HNS which 
bear most directly on an evaluation of their relative 
merits and limitations. 

The judgment of the present reviewers is in accord 
with the principal conclusions of previous assess- 
ments: “ 2,118 HNl and HNS do not possess 

the general utility of H as an offensive agent; and 
(2) that in so far as incapacitation of masked enemy 


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EVALUATION AS WAR GASES 


81 


Table 15. Proper! i 

ies of H, HNl, and HNS bearing 

on their potential effectiveness as war gases. 

Property 

H 

HNl 

HN3 

Storage stability 

Good 

Satisfactory 

Excellent 

Stability on explosion of 
munitions 

Good 

Probably sufficient 

Good 

Stability on terrain 

Good 

Good to poor, depending 
on the nature and 
moistness of the ter- 
rain 

Good 

Density (g/ml, 25 C) 

1.27 

1.09 

1.23 

Load carried by M47A2 
bomb (lb) 

69 (pure H) 71 (Levin- 
stein H = 53 lb of 
active agent) 

61 

67 

Freezing point (C) 

Volatility 

14.2 (pure) ca. 8 (Levin- 
stein) 

-33 + 

-3 + 

mg/1 at 25 C 

0.96 

2.3 

0.12 

relative to H, 10-40 C 

1 

2 . 2 - 2.6 

0.11-0.14 

Median detectable cone. 

(MgA) 

Minimal vapor dosage pro- 

0 . 6 - 1. 8 

13-17 

15 or more 

ducing significant eye 
damage in man (mg 
min/m^) 

100 

>100 

<100 

Relative injury-producing 
effectiveness against 
masked troops without 
protective clothing 

1 

< 1 , much less except 
possibly under hot 
tropical conditions 

1 + 

Injury-producing effective- 

Ineffective in reasonably 

Not known whether 

Ineffective in reason- 

ness of vapor against 

attainable dosages 

casualty production 

ably attainable dos- 

masked troops with 2 
layers of CC -2 impreg- 
nated clothing 


would be feasible 

ages 

Injury-producing effective- 

Ineffective in reasonably 

Ineffective in reasonably 

Ineffective in reasonably 

ness of vapor against 
masked troops equipped 
with clothing containing 
activated carbon 

attainable dosages 

attainable dosages 

attainable dosages 

Relative injury-producing 
effectiveness of liquid on 
bare skin 

1 

1 1 

3 4 

<8 

Relative injury-producing 
effectiveness of liquid 
through CC-2 impreg- 
nated clothing 

? 

? 

? 


troops not equipped with chloramide-impregnated 
clothing is the primary objective in the use of a per- 
sistent agent, HNl and HNS do not possess the of- 
fensive potential of H. At the present time, however, 
it is pertinent to add a discussion of two additional 
points. 

1. The lack of reactivity of HNl and HNS with 
the chloramides used in the United States and Brit- 
ish impregnated clothing of World War II led to 
the inference that this type of clothing would afford 
little protection against the vapors of these agents, 
and that they would therefore be more effective 
casualty-producing agents than H against troops so 
equipped. 118 Recent man-chamber tests at 90 F 
reveal, however, that subjects exposed in 2 layers of 


CC-2 impregnated clothing to 5,000 mg min/m^, 
and in 13 ^ layers to 1,600 mg min/m^, of HNS vapor 
failed to sustain injuries of incapacitating severity. 
Thus CC-2 impregnated clothing affords marked 
protection against HNS vapor, although not neces- 
sarily so much as against H vapor. The explanation 
of this unexpected finding is not at hand. On the 
other hand it has been confirmed that CC-2 impreg- 
nated clothing affords little protection against HNl.'^^ 
However, this lack of protection is at least partially 
offset by the additional evidence that HN 1 vapor is 
relatively ineffective as a vesicant, except possibly 
in very hot weather. 

2. It was the intention of the German Army to 
use HNS in high explosive-chemical shells. In the 


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82 


>'ITROGE>’ MUSTARDS 


opinion of the re^*iewer^, this means of exploiting 
HX3 merits careful evaluation. When HX3 is used 
in this way as a harassing and casualty-producing 
agent, no other kno\NTi gases except the Trilons (see 
Chapter 9) would be expected to approach it in ef- 
fectiveness. It is beheved that in high-explosive 
bombardments an occasional high explosive-chemical 
shell charged HX3 and indistinguishable upon de- 
tonation from ordinan’ high-explosive shell would 
have been used. HX3 j>ossesses the stability to with- 
stand destruction diuing the explosion of the shell 
and the lack of odor to escape ready detection except 
by chemical methods. It is behe^’ed that the pot«i- 
tial harassing and casualty-producing effects of the 
vapor slowly evolved from the contaminated terrain 
might exceed those of the initial cloud. The duration 


of danger from the vapor, the time interx’als required 
for the evolution of casualty-producing dosages, and 
the areas over which effects would be produced would 
depend on meteorolc^cal conditions. As an example 
of the order of magnitude of the hazard, however, 
reference may be made to the field trial data re- 
\'ie\\'ed in Section 6.5 and Table 14. It wiU be noted 
that in iiarm weather explosion of a single M47A2 
bomb (containing 67 pounds of HX3) resulted within 
4 hours in the attaining of a dosage of 100 mg min m* 
of vapor over approximately one-half of an artillery 
square, and of 2^ mg min m* over about one-fourth 
of an artiller\' square. A dosage of 250 mg min m* 
should more than suffice to produce total disabihty 
of several days' duration due to eye injuries, and 
possibly severe respiratoi^v’ injur>’ as well. 


SECRET 


Chapter 7 

ARSE.MCALS 

By Marshall Gates, Jonathan IT. Williams, and John A. Zapp 


7.1 INTRODUCTION 

I N JULY 1917, the Germans not only introduced 
mustard gas into Worid War I, but also employed 
for the first time an arsenical chemical warfare agent, 
diphenylchlorarsine (DA). Other arsenical agents 
were employed by the (jermans in rapid succession, 
phenyldichlorarsine (PD) in September 1917, ethyl- 
dichlorarsine in March 1918, diphenylcyanoarsine in 
May 1918, and ethyldibromoarsine in September 
1918. Although lewisite and adamsite were not actu- 
ally used in battle, the Allies were preparing at the 
end of World War I to use /3-chloro\Tnyldichlorarsine 
(lewisite) and diphenylaminechlorarsine (adamsite), 
and were seriously considering the use of methyl- 
dichlorarsine and arsine itself. 

There was a distinct feehng on the part of the 
Allies that the (Armans did not obtain the maximum 
effectiveness from the arsenicals which they used be- 
cause of technical difficulties in methods of disper- 
sion, and further that some of the agents which did 
not receive battle trial (e.g., lewisite and adamsite) 
might become the most effective agents of their class. 
In \dew of this, it was natural that attention again 
be turned to the arsenical agents at the beginning of 
World War II. Accordingly, both the British and the 
Americans carried out extensive investigations on 
(1) improved methods of preparation of the known 
arsenicals, (2) the preparation of small quantities of 
new arsenicals, and (3) the physiological action, toxi- 
cologj', and assessment of mihtar^" value of these 
agents. Although considerable pn^ress was made in 
the first two categories, none of the arsenical agents 
proved to offer much promise of success in battle for 
reasons which are detailed below. 

7.2 CHEMICAL SECTION 

7J!.i Lewisite 

Lewisite, developed during World War I, is un- 
doubtedly still the best arsenical for gas warfare. 
(For a summary- of worii to 1940, see the bibh- 
ography.)*^ The preparation of the agent by the 
original procedure was comphcated and danger- 
ous; it involves the reaction of acetylene with arsenic 


trichloride, asing aluminum chloride as a catalyst. 
The reaction \ields three products: 

AsCU + H— C^— H aCH=CHAsCl.‘^ 

H 

(acH=CHVAsa ‘^(ctc:b=ch)^\.s 

Lr-2 L-3 

When alumimun chloride is used as the catalyst, the 
ven' xTgorous reaction leads to a mixture in which 
L-2. L-3. tar, and an explosive material are present 
with the desired lewisite. The optimum jdeld of L-1 
in this scheme is about 20 per cent.”^~*^^ It was higjily 
desirable, therefore, to search for other catalj^s. 

The first woiL with a catalyst other than AlCb 
was carried out in Great Britain in 1938.-** where it 
was shown that acetylene can be made to react di- 
rectly with arsenic trichloride in hydrochloric acid 
solution using mercuric chloride as a catalyst. The 
jdeld of L-1 was 80-85 per cent based on the ars«iic 
trichloride and 75 per cent on the acetylene. The 
main drawback to this process was the very corrosive 
nature of the catalytic solutimi. A pilot plant oper- 
ated by the British at Sutton Dak was found capable 
of producing 10 tons per week of “stripped lewisite,” 
which analyzed: L-1. 83.7 per cent; L-2. 11.5 per 
cent ; arsenic trichloride. 2.8 per cent ; solv«it (chlo- 
rinated hydrocarbon) 2.0 per c«it.^* Work; in this 
country showed that a batch process for L 

using a mercuric chloride catalyst is economically 
advantageous. 

Work on other catalyst systems proved cuprous 
chloride used in conjunction with ethanolamine hy- 
drochloride to be (me of the best, both for batch 
and (continuous operations.*-^*-'®-^”-^**-^-^^^-^*** 

Althou^ the reaction rate is somewhat slower 
than with HgCl*- the product is cleaner and there is 
less of a corrosi(m problem. It was also shown ^ 
that the cuprous chloride piwess gives 50 per cent 
more production and 5 per cent greater aretylenation 
efficiency, and that only (medialf the amount of 
thi(myl chloride or phosgene-hydrochloric acid is 
needed in treatment for sludge removal. A plant 
operated by this process at Suttcm Oak produced 
10 tons per week (rf “stripped lewisite. 

Many workers recognized the desirabihty of a con- 


SECRET 


83 


84 


ARSENICALS 


tinuous vapor phase process for the preparation of 
L whereby a mixture of arsenic trichloride vapor and 
acetylene could be passed continuously over a cata- 
lyst. Some degree of success was attained by the use 
of mercuric oxide suspended on alumina in an all- 
glass reactor.®^ With antimony trichloride as an 
activator for the mercuric oxide catalyst, the con- 
version was from 30-40 per cent, with yields of 40- 
60 per cent during the first hour; however, the life of 
the catalyst was quite short. 

Early in World War II, it became apparent that 
there existed a shortage of pure arsenic trioxide used 
in the preparation of arsenic trichloride for lewisite 
production. Consequently two programs were in- 
augurated: (1) the conversion of crude arsenic tri- 
oxide to arsenic trichloride; and (2) the use of arsenic 
trichloride containing impurities in lewisite produc- 
tion by the mercuric chloride process. In a study of 
the latter problem it was shown that arsenic trichlo- 
ride from crude arsenic trioxide can be used directly 
in a lewisite plant. Incidentally it was indicated that 
slightl}^ higher absorption rates were obtained when 
either 2 per cent antimony trichloride or I per cent 
ferric chloride had been added to the arsenic tri- 
chloride.^^ This demonstration led to the observation 
that, when antimony trichloride is included in the 
catalyst layer in the mercuric chloride process, the 
output of lewisite is materially increased. In pilot 
plant operations, it was found that, when the same 
volume of SbCb-containing catalyst (26 per cent 
SbCls added to the standard HgCb catalyst) is used 
in the standard HgCb batch process, the time re- 
quired for acetylenation is reduced by about 40 per 
cent, whereas the amount of Hg present is 72 per 
cent of normal.^^^® 

The problem of using crude white arsenic in 
the production of arsenic trichloride was investi- 
gated first on a laboratory scale and then in a pilot 
plant.^®’^^’^^®’^®^ With the use of three different raw 
materials, one of them containing only 51 per cent 
arsenic trioxide, for reaction with sulfur monochlo- 
ride, yields of 95 per cent based on both arsenic and 
chlorine were obtained in pilot plant runs. With this 
experience as a background the process was trans- 
ferred to the Pine Bluff Arsenal, where about 80 
tons of specification-grade arsenic trichloride was 
produced from two lots of crude arsenic trioxide re- 
covered from ore of the Gold Hill, Utah, deposit. A 
yield of 95 per cent was obtained based on the 
arsenic content of the crude arsenic trioxide. Prac- 
tically all of the arsenic trichloride produced in the 


experimental runs was consumed in the lewisite 
plant with satisfactory results. 

It was also demonstrated that arsenic trichloride 
of high purity can be prepared from either refined 
white arsenic or from low-grade arsenic crudes and 
hydrogen chloride in yields of 97 to 99 per cent based 
on the arsenic content of the raw materials. 

In connection with the use of lewisite as a chemical 
warfare agent it was necessary to study its corrosive 
effect on shell steel. It was shown that plant-grade 
lewisite produced by the mercuric chloride process is 
practically without action on shell steel (No. 1045) 
and may be stored in such steel for long periods of 
time at tropical temperatures with insignificant cor- 
rosion.^® Under these conditions no pressure is devel- 
oped and no deterioration of the lewisite results. 
Phosphorus pentoxide may be used to decrease cor- 
rosion slightly, to eliminate the slight rust formation, 
and to prevent the increase in moisture content under 
damp storage conditions. 

Through other studies it was found that a 1/1 mix- 
ture of lewisite and Levinstein mustard is far more 
corrosive than either constituent alone, and that a 
1/1 mixture of lewisite and thiodiglycol mustard is 
only one-tenth as corrosive as the other mixture.^®-®^ 
The conclusion reached, therefore, is that pure mus- 
tard must be employed if mixtures of it with lewisite 
are to be used in chemical warfare. 

Several investigations were made in order to dis- 
cover agents other than BAL (2,3-dimercaptopro- 
panol-1) which might serve to detoxify lewisite or 
act as antivesicants for it. In a study of the reaction 
products of lewisite and six different dithiols it 
was found that the properties of the compounds are 
best explained by cyclic formulas of the types: 


S— CHR S— CHR 


ClCH=CHAs 


/ \ 

ClCH=CHAs CHR' 

\ / 


S— CH 2 S— CHR 


In a study of the reaction of lewisite with thiols, al- 
cohols, and amines it was shown that the competitive 
rates of formation, or the stability at equilibrium, or 
both, of bonds involving arsenic are in the order 
As — S > As — O > As — N; hence a-dithiols appear 
to be the most satisfactory reagents for detoxification 
of lewisite.®®’®® 

It has been shown that urea peroxide reacts readily 
with lewisite to give a non vesicant product. How- 
ever, a careful investigation failed to reveal a suitable 


SECRET 


CHEMICAL SECTION 


85 


method of stabilizing urea peroxide at 60 C for field 
use."^ Other peroxides were studied and it was found 
that 10 g of a 1/1 mixture of sodium perborate mono- 
hydrate and sodium dihydrogen phosphate mono- 
hydrate, either in the form of a tablet or as a powder 
dissolved in 50 ml of water, gives a solution equiva- 
lent in active oxygen content to a 3 per cent hydro- 
gen peroxide solution. The conclusion was reached 
that BAL if quickly applied is somewhat more ef- 
fective as a preventive for lewisite burns than the 
perborate-phosphate mixture; however, the latter is 
non toxic. 

7.2.2 Aliphatic Arsenicals 

Aliphatic arsenicals in wide variety have been pre- 
pared for testing as candidate chemical warfare 
agents. Major emphasis was placed on alkyldichlor- 
arsines, as it was thought for a while that members 
of this series might show toxicity equal to that of 
lewisite and at the same time exhibit greater chemical 
inertness, particularly in reactions with water. How- 
ever, it was finally established that n-amyl-, isoamyl-, 
and 7i-hexyldichlorarsine, for example, undergo the 
same general reactions as lewisite and react at ap- 
proximately the same rate.^^ There is an apparent 
difference in the behavior of the alkyldichlorarsines 
as compared with lewisite in that the former do not 
liberate a gas when treated with sodium hydroxide 
and the alkylarsine oxides remain in solution longer 
than does lewisite oxide. 

The alkyldichlorarsines have usually been prepared 
by the use of one of the following three schemes: 

1. The Meyer reaction. 

RX NasAsOa ^ IiAs03Na2 ~h NaX 
RAsOsNas + 2H+ ^ RAsOgHs + 2Na+ 

RASO3H2 + SO2 + 2HC1 — ^ 

RAsCb + H2SO4+ H2O 

2. The Kharasch lead alkyl process. 

PbR4 + 3AsCl3 — > 3RAsCl2 + PbCb + RCl 

3. From arsenic trichloride and tertiary arsines. 
R3AS + 2ASCI3 — ^ 3RAsCl2 

The Meyer scheme is the one most frequently 
used. ’2® -28. 32 . 39, 58 . 129 , 290 j becomes less efficient with 
the higher alkyl halides, such as heptyl bromide. The 
Kharasch process is particularly good for the prepa- 
ration of ethyldichlorarsine in view of the availa- 
bility of tetraethyllead.'^* The suitability of the proc- 
ess for large-scale production has been demonstrated 
by pilot plant operations in which the reaction went 
readily and smoothly giving a 90 per cent yield. 


For the preparation of dialky Ichlorarsines, four 
principal routes have been followed. 

1. The Meyer reaction. 

RAsCb + 4NaOH — > 

RAs(ONa)2 + 2NaCl + 2H2O 
RAs(ONa)2 + R'Br — > RR'As02Na + NaBr 
RR'As02Na -j- SO2 + HCl — > 

RR'AsCl + NaHS04 

2. The Kharasch lead alkyl process. 

3RAsCl2 + R;Pb ^ 3RR'AsCl + R'Cl + PbCb 

3. The cacodyl process. 

4RCOOH + AS2O3 2H2O + 4CO2 + (R2As)20 
(R2As)20 + 2HC1 — ^ 2R2ASCI + H2O 

4. From arsenic trichloride and tertiary arsines. 
2R3AS + AsCls — > 3R2ASCI 

Here, as in the case of the alkyldichlorarsines, the 
Meyer reaction scheme is the one most commonly 
followed. ^-®-2*'82.39.58 However, work on the cacodyl 
process 8,17,131 resulted in a marked improvement 
in this classical reaction. The improvement is in the 
form of a continuous catalytic process wherein va- 
pors of the acid and arsenic trioxide are passed over 
an alkali salt on a pumice support. Although this 
process was previously identified only with the pro- 
duction of dimethylarsine derivatives, it has been 
demonstrated that higher homologs may be pre- 
pared in fair yield. 

In the preparation of tertiary arsines, three general 
reaction schemes have been used : 

1. Reaction of Grignard reagents with AsCb, 
RAsCb, or R2ASCI. 

3RMgCl + AsClg ^ R3AS + 3MgC]2 
2RMgCl + R'AsCb ^ R2 R'As + 2MgCl2 
RMgCl + RaAsCl RR2AS + MgCb 

2. Reaction of alkylmercuric chloride with arsenic 
trichloride. 

3RHgCl + AsCb ^ RsAs + 3HgCl2 

3. Disproportionation of RAsCb or R2ASCI. 

2RASCI2 ^ R2ASCI + AsCb 
2R2ASCI ^ R3AS + RAsCb 
RAsCb 4“ R2ASCI ^ ^ R3AS -}- AsCls 

It should be noted that all these methods are labo- 
ratory procedures and that no large-scale prepara- 
tion of an aliphatic tertiary arsine has been at- 
tempted.^ 


SECRET 


86 


ARSEMCALS 


7.2.3 Aromatic Arsenicals 

The standard approach to an aromatic ai-senical is 
the Bart reaction between an aiAddiazonium halide 
and sodium arsenite: 

ArNsCl + NasAsOs — ^ ArAs 03 Na 2 + XaCl + X 2 
ArAs 03 Xa 2 + SO 2 + 2HC1 — > 

ArAsCb + Xa 2 S 04 + H 2 O 

^lany aromatic ai*senicals desired in the toxico- 
logical testing program have been prepared in this 
manner. However, the only aromatic arsenicals 
produced on am" sizable scale during World War II 
are diphenylchlorarsine (DA) and diphenylcyano- 
arsine (DC). Considerable attention was devoted by 
the British to process development studies of those 
compounds.^*® They carried out laboratory" and 
large-scale tests on two processes for DA prepara- 
tion: 

1. The Pope-Tumer process. 

C6H5.\sCl2 + H 2 O — ^ C6H5.\sO + 2HC1 
C 6 H 5 ASCI 2 + 3C6H5.\sO — ^ 2(C6H5)2AsC1 + AS 2 O 3 

2. The double diazotization process. 

C 6 H 5 X 2 CI -j" Xa 3 As 03 ^ 

C6H5.\sO(OXa)2 + X 2 + XaCl 

C6H5.\sO(OXa)2 + XaHS03 — > 

C6H5As(OXa)2 + XaHS04 

C6H5.\s(OXa)2 + C 6 H 5 X 2 CI — > 

(C6H5)2AsOOXa -h X2 H- XaCl 
(C 6 H 5 ) 2 AsOOXa + SO2 + HCl — ^ 

(C6H5)2AsC 1 + XaHS04 

A considerable improvement in the Pope-Tumer 
process was effected by the British workers,^®® who 
worked out the proper conditions for partial hy- 
drolysis of phenyldichlorarsine to a stoichiometric 
mixture of phenylarsine oxide and phenyldichlor- 
arsine (3/T mixed oil), which, when heated to 240- 
250 C, was converted to DA in good yield. DA is 
readily transformed to DC by" reaction \rith 30 per 
cent aqueous sodium cyanide at 35-40 C.^®® 

7.2.4 Heterocyclic Arsenicals 

From the standpoint of large-scale preparation 
work, only" one member of this group, adamsite 
(DH), was considered important during World 
War II. However, representatives of several other 
heterocyclic ty"pes were prepared for toxicity^ testing. 

Adamsite is still prepared by the standard pro- 
cedure worked out during World War I and involv- 


ing the reaction of dipheny"lamine with arsenic 
trichloride : 

(r'x) 


It has been shown ^ that a considerable part of the 
arsenic trichloride called for in this equation may be 
replaced by the less expensive arsenic trioxide with- 
out a sacrifice in y-ield. 

Furan arsenicals were studied both in this country- 
and in Great Britain.-® ’^®^* They were prepared by 
reacting a-chloromercurifuran vdth arsenic trichlo- 
ride to give trifury-larsine. From this tertiary arsine 
the mono- and di-furyd-chlorarsines were made by 
reaction ^rith arsenic trichloride. Similarly- thiophene 
arsenicals were made from a-thieny-hnagnesium 
bromide and arsenic trichloride ^ and py-ridine arsen- 
icals were obtained from 3-aminopy-ridine by the 
Bart reaction.®* 

Other miscellaneous heterocy-clic arsenicals pre- 
pared for toxicity- testing include 5,10-dichloro-5,10- 
dihy"droarsanthrene,^’®®^^’*’^’‘'’“ dibenzarsinole chlo- 
ride,®*®'^ and 10-chloro-9,10-dihy"droarsacridine.®*' 
307i,i.k,m,n "pjjp preferred methods of preparation are 
illustrated by- the follovdng equations. 

1 . 5, lO-Dichloro-5, 10-dihy-droarsanthrene. 




0 — AsO^Xa- 

-xo. 


0 — AS 03 H 2 

-N,C1 


O OH 



O OH 



SECRET 


PHYSIOLOGICAL SECTION 


87 


2. Dibenzai-sinole chloride. 


^ ^ + Na3.\s03 — > 

CIN2 

o>-o>-o>-^ 


Na203As 


H 203 .\S 


< 0-0 


H2O3AS 




3. lO-Chloro-9, 10-dih3^droarsacridme. 



AsOsXao ASO3H2 



O OH Cl 


7.3 PHYSIOLOGICAL SECTION 


7.3.1 Lewisite 

When the United States became actively involved 
in chemical warfare during World War I, high hopes 
were held for a new agent, )3-chlorovin\ddichlor- 
arsine, which was prepared and suggested as a candi- 
date agent by Capt. W. Lee Lewis in 1917. On the 
basis of relatively meager laboratory data it was de- 
cided to produce this agent, Le\visite (L), in quantity 
and to use it in battle. A shipment was on its way to 
Europe when the war ended in November 1918. 

During 1918, and particularly during the latter 
half of the year, the toxicological properties of L were 
studied intensively in various laboratories of the 
Chemical Warfare Service. The data obtained dur- 
ing this period are well summarized and ^\^ll not 
be discussed in detail in this report. However, two 


reports issued in 1919 are particular^ interest- 
ing in that they not onty summarize the toxicological 
data acquired during the war period but also attempt 
to assess the military value of L as a chemical agent. 
Since the conclusions of 1919 offer a convenient start- 
ing point from which to consider the later develop- 
ments which took place in the interval between wars 
and during World War II, these conclusions wdll be 
briefly stated. 

The effects of liquid L on the skin were studied in 
detail on dogs and rabbits.^^ It was felt that L was 
definitely more damaging to the skin than H and that 
the danger of systemic poisoning from L was con- 
siderably^ greater than \s’ith H. It was concluded that, 
if man were as susceptible as dogs to systemic poison- 
ing from L, the minimum lethal dose for man would 
be 1.4 ml distributed over an area of 5 square inches 
for an individual of average size. 

No systematic study of the effect of liquid L on 
human skin was carried out. However, it was stated 
that: 225 

Laboratory workers who have been accidentally burned 
vsith liquid L have given strong evidence for the greater ef- 
fectiveness of this substance in man than liquid H. The L 
lesions develop with extreme rapidity, are painful and associ- 
ated with definite constitutional symptoms. The lesion is not 
confined to the skin, but extends to the deeper tissues. In heal- 
ing, dense scar tissue forms, the skin loses its flexibifity and 
contractures may develop. With liquid H skin bums in man, 
pain is less or absent, there are no constitutional symptoms, 
the amount of skin destruction is less, and healing occurs with- 
out extensive scar formation, formation of contractures, or 
permanent disability. 

In view of the divergence of these \dews from those 
currently accepted, it is well to bear in mind that 
these were accidental bums and hence were probably 
treated, that the accepted treatment at the time was 
application of 5 per cent sodium hydroxide to the 
lesion for a period of 30 minutes, and that sodium 
hydroxide itself in that strength produces a very 
destructive skin effect. 

The effects of L vapor on the skin were studied 
\\'ith dogs, rabbits, and man, and are summarized in 
Table I .225 

Table 1. Approximate concentration to produce skin 

lesions in 30-minute exposure. 



Rabbit 

Dog 

Man 

Lewisite (L) 

0.025 mg/1 

0.050 mg/4 

0.200 mg/1 

Mustard (H) 

0.200 mg/1 

0.050 mg/1 

0.025 mg/4 


The comparison indicated a lower sensiti\dty of 
man toward L vapor than toward H. The degree of 


SECRET 


88 


ARSENICALS 


protection afforded by ordinary wet and dry clothing 
against L and H vapor was also studied. 

It was concluded: 

An approximate concentration of .200 mg/1 (of L) is neces- 
sary to produce skin lesions in man on exposure of one-half 
hour. To be effective on parts of the body covered with cloth- 
ing, it would be necessary to raise this concentration from 
three (3) to one hundred (100) times, or approximately to a 
concentration of .600 to 20.0 mg/1 ... So far as the concentra- 
tion required under field conditions to produce cutaneous 
lesions in man, H should be regarded as from eight (8) (on 
unprotected skin) to a thousand (1000) times (a single layer 
of wet wool) more effective than L. 

The eye effects of L vapor were studied on rabbits 
and dogs. As with skin effects, it was found that rab- 
bits were more susceptible to L vapor than were dogs, 
and a comparison with H revealed that the relative 
susceptibility of the species toward L and H vapor 
paralleled that of the skin effects. The data are sum- 
marized in Table 

Table 2. Approximate concentration necessary to pro- 


duce eye lesions 

in 30-minute exposure. 



Rabbit 

Dog 

Man 

Lewisite (L) 

0.001 mg/1 

0.020 mg/1 


Mustard (H) 

0.050 mg /I 

0.020 mg/1 

0.001 mg/1 


The statement was made : ‘Tf we may be allowed 
to infer or judge of the susceptibility in man without 
having an actual determination, the conclusion 
would be that the eye of man is less susceptible to L 
than to H, but such a conclusion can never convey 
the conviction as one based on actual determina- 
tion.’’ No experiments involving the effects of liquid 
L on the eye were reported. 

The respiratory effects of L vapor were studied on 
dogs and compared with the effects of H vapor, it 
being found that the dog was approximately twice 
as susceptible to L as to H. It was pointed out 
that the concentration necessary to produce death in 
man on respiratory exposure is not known in the case 
of either H or L, but that ‘hn the light of our present 
knowledge we can only conclude that on respiratory 
exposure, L is to be regarded as approximately twice 
as effective as H as determined by the concentration 
necessary to kill. This conclusion, as applied to man, 
must be made with reservation due to deficiency 
of data.” 

With respect to the relative military value of L 
and H, it was stated : ^25 

In attempting a comparison of the relative military value 
of the substances H and L, we meet with the fact that while 
with the former substance we have a very large experience 


from the laboratory, the experimental field and the field of 
war, our knowledge of the latter is confined entirely to data 
from the laboratory. The abrupt cessation of experimental 
work at the American University following the signing of the 
Armistice in November 1918, prevented the carrying out of 
field tests with L, preparations for which were already under 
way. 

In summary of the situation in 1918 it was 
stated : 

We regard the laboratory data as offering strong support for 
the probability that L will prove to have great military value. 
Its actual value can only be definitely determined, however, by 
further experimental data, especially those obtainable by field 
tests. It would furthermore seem clear that the usefulness of L 
in war would differ quite widely from that of H. Little effect 
should be expected from the vapor- when used against troops 
supplied with an efficient mask equipment, because of the low 
skin vapor toxicity and the resistance of clothing to penetra- 
tion of the vapor. This is the condition, on the other hand, in 
which H has been found most effective. The usefulness of L 
would be confined to the effect of the substance reaching troops 
in the liquid phase (splash or mist) by their coming in contact 
with contaminated material, the influence of the hydrolytic 
products in contaminating the ground and objects, and the 
respiratory effects and possibly the eye effects of the vapor in 
the case of troops unprotected by mask equipment. In those 
respects L offers many advantages, so far as can be concluded 
from the data at hand, over H. We feel that L offers sufficient 
promise to warrant the most careful further consideration. 
Data which are not at present obtainable and which are most 
desirable in this connection are as follows: 

1. The keeping qualities in steel. 

2. The ability of the substance to withstand detonation. 

3. The vapor concentration which it is possible to secure 
and maintain in field tests. 

4. The vapor concentration necessary to produce eye le- 
sions in tests on man. 

5. The relative importance of burns by liquid H and vapor 
of H in actual warfare. 

In conclusion we wish to repeat: We believe that L will not 
replace H in warfare, and that in any plans for military oper- 
ations the production and utilization of H should remain one 
of the most important propositions. While very promising, the 
military value of L remains to be established. 

In the interval between 1919 and 1940 relatively 
little research on the toxicology of L was carried out 
by the Chemical Warfare Service, with the exception 
of a detailed study which was published in 1923.^^^ 
This report has been critically reviewed and will 
not be discussed in detail, although a few of the re- 
sults will be mentioned later in the present report. 
It was concluded that L is superior to H in that 
it gave deeper and more severe burns as well as sys- 
temic disturbances leading to death, but the diffi- 
culty of setting up effective vapor concentrations 
was recognized. 

Following the publication in the open litera- 


SECRET 


PHYSIOLOGICAL SECTION 


89 


ture of information that L had been seriously 
considered by the Americans as a war gas, the agent 
was studied in the laboratories of other nations. The 
published German reaction was unfavorable. The 
compound was tested in German}^ in 1916 and 
the conclusion reached that it was not reliable as a 
war gas because its toxic effects were less lasting than 
those of mustard and the irritant effects were so 
marked that men would be warned in time of its 
presence. The opinion was offered that the Ameri- 
cans were spared a great disappointment by being 
unable to use L in World War I. A series of experi- 
ments was carried out in which the effects of rela- 
tively large doses (one to two drops from an ordinary 
eye dropper) of H and L on human skin were com- 
pared. These experiments, published in 1932, led to 
the conclusion that L was inferior to H in producing 
skin injury and that its potentialities as a war gas 
have been greatly overrated. In reference to the cal- 
culation that 1.4 ml of L applied to the skin of 
a man should be the approximate minimum lethal 
dose, it was asserted that this amount was applied 
repeatedly to the skin of human beings without giv- 
ing evidence of systemic intoxication.^^® The Japa- 
nese used a 1/ 1 mixture of H and L against the Chi- 
nese at Ichang in 1938, but subsequent information 
obtained by the interrogation of Japanese officers 
revealed that the L was added mainly to lower the 
freezing point of the H. 

The value of L as a chemical warfare agent still re- 
mained to be established in 1941. The published Ger- 
man opinions were looked upon with distrust, and, 
as in World War I, the United States undertook the 
quantity production of L. The discrepancies in the 
literature as to the toxicological effects of L had to be 
resolved and intensive research was carried out both 
in the United States and Great Britain. 

Properties of Lewisite 

Plant run L is usually dark brown in color and pos- 
sesses an odor reminiscent of geraniums. Both the 
color and odor are due to impurities, which can be 
removed if the extra effort involved is considered 
worth while. Cis- and trans- isomers exist which 
have almost identical toxicities.^^® L freezes at 
— 18.2 C to 0.1 C, depending on the purity and 
isomers present. The density of liquid L is 1.886 at 
20 C, whereas the density of the vapor is 7.1 com- 
pared to air. The volatility of L is greater than that 
of H and increases somewhat less rapidly than that 
of H with increasing temperature. The following data 


for L are calculated from the vapor pressures; 
comparative data for H are also given.®® 


Temperature 

Volatility (mg/1) 

Ratio L/H 

C 

L 

H 


0 

1.06 



10 

2.23 



15 

3.29 

0.41 

8.0 

20 

4.48 

0.65 

6.9 

25 

6.14 

0.96 

6.4 

30 

8.62 

1.39 

5.1 

35 

11.32 



40 

15.75 

2.82 

5.6 


L is fairly stable on storage in glass or steel but is 
degraded to a considerable extent on detonation. 

The reaction of L with BAL and certain related 
dithiols 30Df-3oor,3i5 form non toxic complexes has 
assumed great importance in the treatment of L 
lesions and of arsenical poisoning from L or other 
sources. 

The chemical properties which most sharply limit 
the usefulness of L as a chemical warfare agent are 
the ease with which it reacts with (1) water and 
(2) alkalies. In contact with water or moist surfaces, 
lewisite is readily hydrolyzed to the oxide which, 
although mildly vesicant, is nonvolatile and insolu- 
ble in water. Since L “precipitates out” in contact 
with moist surfaces it is impossible to maintain high 
vapor concentrations in humid atmospheres. Alkalies 
decompose L rapidly at ordinary temperatures, and 
even alkaline soil rapidly destroys the liquid and 
imposes a further limitation on its use as a ground 
contaminant. The maximum efficiency of L is only 
attained, therefore, under conditions of low temper- 
ature or low humidity, both of which minimize hy- 
drolysis, and on dry nonalkaline terrain. 

Physiological Action 

Lewisite Vapor. The qualitative effects of L on the 
eyes, skin, and respiratory tract have been described 
in the open literature 21 8.330 have also been re- 

cently summarized.®^® They may be very briefly re- 
stated as follows: 

1. Eyes. L vapor is extremely irritating to the 
eyes, causing pain, lacrimation, and blepharospasm. 
The lacrimation and blepharospasm protect in a 
large degree from further exposure to the vapor but 
if the Ct is sufficiently high the irritation and pain 
persist and after a few hours are followed by edema 
of the eyelids and conjunctivitis. Permanent damage 
is, however, apt to result only from very high con- 
centrations difficult to achieve in the field. 

Liquid L is capable of causing severe damage to the 


SECRET 


90 


ARSENICALS 


eyes. Pain, lacrimation, and blepharospasm appear 
immediately, and are followed by edema of the lids, 
iritis, and conjunctivitis. In severe contamination, 
ulceration, necrosis, and secondary infection may 
lead to blindness or to permanent impairment of 
vision. 

2. Respiratory tract. L vapor is irritating to the 
na.sal passages and produces a burning sensation 
followed by profuse nasal secretion and violent sneez- 
ing. On prolonged exposure coughing results and 
large quantities of frothy mucus may be brought up. 
The effects of L vapor are so prompt and striking 
that men usually mask before enough of the com- 
pound is inhaled to produce serious injury. However, 
in experimental animals exposed to vapor in a gas 
chamber, injury to the respiratory tract is essentially 
similar to that produced by mustard. Edema of the 
lung is often more marked and is frequently accom- 
panied by pleural fluid. 

3. Skin. L vapor usually produces no more than 
erythema of the skin, although if the skin is hot and 
dry and the vapor concentration is high, small, shal- 
low, turbid blisters may develop and may coalesce to 


form large vesicles. Such conditions would seldom 
be realized in the field. 

Liquid L on the skin produces an immediate sting- 
ing sensation which fortunately warns of its presence. 
If L is allowed to remain on the skin for 5 minutes, 
the site of application assumes a cooked appearance, 
somewhat resembling that from an acid burn. Ery- 
thema develops in a short time around the site of 
contamination and is followed by vesication of the 
entire erythematous area. L can penetrate the skin, 
subcutaneous tissue, and muscle, causing extreme 
edema and necrosis. 

The fluid contained in vesicles produced by L tends 
to be more opaque than that found in mustard blis- 
ters, although it is frequently impossible to distin- 
guish L vesicles from mustard vesicles by their 
appearance. 

The fluid from an L blister contains 0.8 to 1.3 7 of 
arsenic per cubic centimeter, equivalent to 2.5 to 
4.0 7 of original 

4. Systemic effects. The absorption of a sufficient 
amount of L through the skin of dogs may lead to 
death within 24 hours and usually within 10 hours. 


Table 3. Toxicity of L vapor. (All figures are LfCOso in mg min/1, exposure time = 10 min, observation 
period 10 days, except as noted.) 


Species 

Total 

exposure 

Inhalation only 
exposure 

Body only 
exposure 

Mouse 

0.9-1. 4 (nom.)'' 

1.4-1. 5 (nom.)^' 

1.2-1. 9 (nom.)^' 

Mouse 

2.8 (nom.)27 

1.6 (nom.)*2® 

0.3 (nom,)*2e 

Mouse 

1.5 (anal.y^ 

1.5 (anal.)82e 

7.0 (nom.)"*® 

Mouse 

2.5-2.8 (nom.)i'6 



Mouse 

0.5 (anal.)268.* 



Rat 

1.5 (anal.)258.t 


20.0 (nom.)« 

Rat 

0.58 (anal.)258.t 

. 


Guinea pig 

1.0 (anal.)^®*’* 


20.0 to 25.0 (nom.) «•§ 

Guinea pig 

0.47 (anal.)258q 



Rabbit 

1.2 (anal.)258.|| 


15.0 (nom.)'5 

Rabbit 

1.5 (anal.)268.^ 



Goat 

1.25 (anal.)258.** 



Cat 



30.0 (nom.y^’n 

Dog 

1.4 (nom.)ii6.§§ 


30.0 (nom.)*2‘‘qj 




40.0 (nom.)^5 


* 9- to 14-min exposure. 21-day observation period, 

t 9- to 25-mi n exposure. 21-day observation period. 

X 60- to 180-min exposure. 21-day observation period. 

§ 10- to 40-min exposure. 

II 7.5- to 13-min exposure. 21-day observation period. 

^ 60- to 310-min exposure. 21-day observation period. 

** 100- to 255-miu exposure. 21-day observation period, 
ft 30- to 45-min exposure. « 

30- to 60-min exposure. 

§§ {Ct = 1.32 for 7Lniin exposure and 1.44 for 15-min exposure, 93-hour observation period. The report states that concentrations were determined 
both as nominal and analytical but only one set is given and it is not characterized.) 

Note. Nom. = nominal concentration; i.e., concentration calculated from the amount of L volatilized, the flow rate, and the duration of flow. 


Nominal concentration = 


Amount volatilized (mg) 
Flow rate (1/ min) X Time (min) 


= mg /I 


Anal. = analytical concentration; i.e., concentration determined by sampling and chemical analysis of the atmosphere. 


SECRET 


PHYSIOLOGICAL SECTION 


91 


A few hours after application, the dogs show evidence 
of severe intoxication and appear almost moribund. 
Death apparently occurs from an intoxication which 
interferes with certain vital processes without pro- 
ducing sufficient anatomical lesions for complete 
characterization of the immediate cause of death. A 
frequent accompaniment of systemic intoxication is 
a change in capillary permeability which permits loss 
of sufficient fluid from the blood to result in hemo- 
concentration and profound shock. The blood vol- 
ume of dogs was observed 224 to fall as low as 3.9 per 
cent of body weight in burned animals (normal = 
9.7 per cent). 

Nonfatal cases may develop a hemolytic anemia, 
focal necrosis of the liver, and some injury to the in- 
testinal mucosa. 

Toxicity. There is no disagreement over the fact 
that L is a highly toxic compound and that it can 
produce the physiological effects which have been 
described. In order to evaluate the usefulness of L as 
a chemical warfare agent, however, several things 
must be known. These are: 

1. What dosages of L are required to kill men or 
at least to make them casualties? 

2. Can these dosages be attained in the field with 
a reasonable expenditure of munitions? 

3. How easily can the soldier protect himself 
against the effects of L? 

4. Are the results obtainable through the use of L 
in the field likely to be better or worse than those 
obtainable with the standard vesicant agent, H? 

Toxicity Data 

The answer to (1) can only be approached experi- 
mentally through studies on animals. The toxicity of 
L vapor toward animals of different species is shown 
in Table 3. The L(C^) 50 of L vapor for man is un- 
known, but may be estimated (from the data of 
Table 3) to be of the order of 1.2-1. 5 mg min/1 (ana- 
lytical). The L{Ct) 5 o for body exposure only has been 
estimated to be of the order of 100,'*^ on the basis of 
animal experiments and with the assumption that 
the absorption of L through the skin is a function of 
the ratio of surface exposed to body volume. 

The toxicity of liquid L applied via the skin for 
animals of different species is shown in Table 4. On 
the assumption that man would be as susceptible as 
the dog, it was calculated in 1919 that the LD 50 
for a 70-kg man would be of the order of 1.4 ml of L 
applied over an area of 5 square inches of skin. It is 
stated, however, that doses of 1.4 ml can be applied 


Table 4. Toxicity of lewisite by skin application. 


Animal 

LDsoCmg/kg) 

Reference 

Mouse 

15 

87 (Cited by Smith) 

Rat 

24 

300f 

Rat 

15 

318 

Rat 

24 

249 

Rat 

20 

318 

Rabbit 

5 

318 

Rabbit 

6 

249 

Rabbit 

6 

133 

Guinea pig 

12 

249 

Dog 

38 

224 

Dog 

ca. 70 

295a 

Goat 

24 

241 

Goat 

10 

217 


repeatedly to men without eliciting any clear-cut 
symptoms of arsenical poisoning.^^^ The LDoo for 
man is probably much greater than the 40 mg/kg 
sometimes assumed. A case is reported in which a 
worker at Pine Bluff Arsenal suffered accidental 
lewisite burns over 20 per cent of his body surface 
(mostly on the legs). He showed an anemia 10 to 15 
days after the burn, but no clear-cut signs of systemic 
arsenical poisoning. It appears, therefore, that man is 
not nearly so susceptible to systemic arsenical poison- 
ing from skin contamination with L as was originally 
believed. 

The toxic dose of L when administered parenterally 
is much lower than that required by skin absorption. 
For example, the LD^o for rabbits is stated in one 
British report to be 2 mg/kg by either intravenous 
or subcutaneous injection, and in another to be 
0.5 mg/kg b}^ intravenous injection. The intravenous 
LDso for dogs was found to be 2 mg/kg as compared 
to 38 mg/kg by skin absorption. Two mg/kg, 
injected intraperitoneally, has been given as the 
minimum fatal dose for guinea pigs.^^®"^ 

It is difficult to see, however, how the enhanced 
toxicity by parenteral administration can be utilized 
in warfare. 

Casualty production by L may result from the 
action of the vapor on the respiratory tract, or of the 
vapor or liquid on the eyes and skin. Assuming that 
men will be masked, the probabilities of casualty 
production from the inhalation of vapor are small. 
Relative to the eyes, it has been shown that for L to 
produce moderate corneal damage in dogs a vapor 
Ct of 2.8 mg min/1 (nominal) is required; whereas a 
destructive lesion is produced by a Ct of 5.5 (nom- 
inal). Analytical concentrations in the above ex- 
periments were approximate!}" 50 per cent of the 
nominal so that an analytical Ct of the same order as 


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ARSENICALS 


the L{Ct)iQ by inhalation is required to produce mod- 
erate eye damage. Since the immediate response of 
the eye to L vapor is lacrimation and blepharo- 
spasm, both of which protect against further expo- 
sure, serious eye casualties from L vapor are not to be 
expected in conscious men. 

Liquid L in the eyes is capable of producing de- 
structive lesions. It has been estimated that a 
drop 170 M in diameter in the eye of a man would 
make him a casualty for over a week unless immedi- 
ately treated. A 0.1-mg drop in the rabbit eye caused 
perforation of the cornea in approximately 75 per 
cent of the cases and permanent disability (as judged 
by the persistence of corneal haze) in nearly all 
cases. In the rabbit eye a 0.1-mg dose of liquid L 
produces a maximal lesion. With doses greater than 
0.1 mg the severity of the ocular reaction did not 
appreciably increase. It has been stated that a dose 
of 0.01 to 0.02 mg of liquid L will produce permanent 
ocular damage (in rabbits) approximately equal to 
that produced by 0.1 to 0.2 mg of liquid H. With 
0.05 mg of L most of the eyes are completely de- 
stroyed, whereas even 1.4 mg of H does not produce 
an equally severe lesion. Mild, self-limiting injuries 
of comparable severity are produced by 0.005 mg 
of L and 0.02 mg of H. It is thus apparent that the 
severity of the L lesion increases steeply with in- 
creasing dosage and rapidly reaches a maximal lesion, 
whereas the curve relating severity of the lesion to 
dosage of H is much more flat and very large doses 
are required to destroy an eye completely. 

The threshold Ct for vesication of bare human 
skin (forearm) has been estimated as 1.0 mg min/1 
(analytical) for a temperature of 55 F and relative 
humidity = 70 per cent.^^* A Ct of 1.8 at T = 90 F 
and relative humidity = 49 per cent caused vesica- 
tion of the bare hand in 50 per cent of the men ex- 
posed. A Ct of 1.5 (analytical) caused vesication of 
the neck of six men exposed in the field at T = 66 F 
and relative humidity = 41 per cent, but no effect 
was obtained on skin covered by ordinary battle 
dress.2^* A Ct of 1.5 (analytical) at T = 90 F and 
relative humidity = 65 per cent caused vesication 
on the skin (forearm) of three men (3/3), whereas 
a Ct of 1.2 produced vesication in none of three 
men (0/3) under the same conditions of temperature 
and humidity. 

Liquid L on the bare skin is a very potent vesicant, 
the median threshold blistering dose for man being 
14 ^xg as compared with 32 for Contrary to 
the opinions held in this country prior to World 


War II, recent work has tended to establish the 
view that in relatively large amounts L does not 
produce as severe skin damage in man as does H. 
Although with doses up to about 1 mg of liquid L 
produces skin lesions in men not perceptibly differ- 
ent from those resulting from the same amount of 
liquid H, the response to larger doses of the two 
agents is different. For 2-mg dosages of L and of H, 
the lesions produced by L are less severe and heal 
in 2}/2 to 4 weeks compared to the 5 to 9 weeks re- 
quired for healing of the mustard lesions. One investi- 
gation,^^® using much larger doses, placed two large 
drops (from an ordinary eyedropper) of L on one 
forearm and of H on the opposite forearm of a man. 
He reported healing of the L lesions in 26 days and 
of the H lesions in 63 days and stated that these re- 
sults were typical of other experiments. It has been 
pointed out that in rabbits the damage produced by 
2 mg of liquid L is more severe and slower to heal 
than that produced by 2 mg of liquid H. The reaction 
of rabbit skin toward L is, therefore, not character- 
istic of the reaction of human skin. In an investiga- 
tion conducted at Porton it was concluded that L 
burns heal more quickly than H burns, are less prone 
to infection, and cause less pain during healing. The 
question of the comparative severity of lesions pro- 
duced by H and L on human skin has recently been 
reinvestigated,^^® with the result that L lesions were 
found to be less severe and to heal more quickly than 
those caused by the same amount of H (either by 
weight or by volume, the dose being 1.0 mg or 
0.5 microliters). 

It may be noted parenthetically that in 1941 a 
statement appeared in United States official chemical 
warfare manuals to the effect that the fluid from 
lewisite bullae was itself vesicant. Plowever, experi- 
ments have been reported leading to the conclu- 
sion that L blister fluid was neither vesicant nor 
irritating and an American investigation in 1943 
confirmed this conclusion, with the result that state- 
ments regarding the vesicancy of L blister fluid have 
been withdrawn from recent editions of United 
States official manuals. 

The toxicity of L for man is summarized in Table 5. 

The dosages required for L to produce casualties 
in men or to kill them appear to have been as well 
established as would be possible through the use of 
experimental animals in lethal experiments and hu- 
man observers in marginal experiments. 

As was aptly stated in 1919 the value of L as a 
military agent depends in large degree on whether 


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PHYSIOLOGICAL SECTION 


93 


Table 5. Toxicity of lewisite for man. 



Vapor 

approx. L(C05 o 
( analytical) 
mg min /I 

Liquid 

dose 

mgso 

Death (by inhalation) 

1.2-1. 5 (est.) 


Death (by body exposure) 

100 (est.) 

2,800 (est.) 

Vesication of skin (bare) 

1.2-1.5 

0.014 

Serious corneal damage 

1.5 (est.) 

0.1 (est.) 


the necessary dosages can be set up in the field. Suf- 
ficient field experiments have now been carried out 
to indicate that the requisite dosages are probably 
not attainable with any reasonable expenditure of 
munitions. 

Field Test Data 

The concentration of vapor obtained from pouring 
50-75 g of L per square yard on the ground is low 
and Ct values obtained are usually not over 4.0 mg 
min/l.^^'*’^^® The vapor concentration obtained di- 
rectly over the contaminated area fell steeply during 
the first 30 minutes of the experiments and thereafter 
was not dangerous. 

In experiments conducted at Edge wood Arsenal 
four M70 bombs charged L (total 360 pounds) were 
fired statically. Twenty-five yards downwind from 
the burst the initial concentration was 0.060 mg/1 
but fell to 0.013 mg/1 in 10 minutes. The Ct for 15 
minutes was 0.395 mg min/l.^^® In a further test at 
Edge wood an airplane sprayed 610 pounds of un- 
thickened L from an altitude of 75 feet over an area 
of 76,250 square yards. Significant vapor concen- 
trations directly over the contaminated area were 
recorded only for the first 10 minutes and the total 
Ct recorded was of the order of 3. 

It is apparent from the above examples that dan- 
gerous concentrations of L vapor are difficult to at- 
tain in the field. The reason for this is apparently 
the rapid hydrolysis of the vapor and liquid in con- 
tact with a moist environment, with possibly the 
destruction of some L by alkaline soil, together with 
the fact that the agent may be partially destroyed 
by detonation when loaded in munitions. In ex- 
tremely hot and dry climates more effective vapor 
concentrations may be anticipated. 

The effects of liquid L on bare skin might be 
achieved through ground contamination, bursting 
munitions, or airplane spray. However, L is so un- 
stable on contact with moisture that under ordinary 
conditions of humidity it is rapidly h 3 ^d roly zed on 
the surface of soil or foliage, leaving behind a residue 
of L-oxide. The L-oxide, while weakly’ vesicant, is 


nonvolatile and insoluble in water and is only effec- 
tive when brought in contact with bare skin. If the 
soil is alkaline a part of both the original L and the 
oxide may be completely destroyed. The British 
attempted to assess the danger of systemic intoxica- 
tion from liquid L released in bomb explosions. On 
the assumption that the lethal dose for man would 
be 1.9 g (a dose which is probably not fatal) it was 
concluded that the risk of receiving serious injury 
from a bomb charged with L would be no greater 
than from a bomb of the same size charged with high 
explosive. When un thickened L is released from an 
airplane spray tank, the droplets formed are less than 
1 mm in diameter. Since it has been reported 229,230 
that L droplets of less than 1 mm in diameter evap- 
orate completely while falling through 2,000 feet, it 
is apparent that the employment of unthickened L 
from medium altitudes (>2,000 feet) as airplane 
spray would be useless. L may be thickened with 
methyl methacrylate and similar materials. The use 
of thickened L as airplane spray results in larger 
drops (55 per cent of drops >0.5 mg as compared 
with 8 per cent of drops >0.5 mg for unthickened 
L).^®^ However, when droplets of thickened L strike 
a surface, they tend to harden. This effect may be 
due to the formation of a skin of L-oxide on the sur- 
face of the drop.^®^ 

A comparison of the casualty-producing effect of 
thickened and un thickened L when used as an air- 
plane spray from low altitude (100 feet) revealed that 
thickened L was less effective in producing casualties 
in goats than unthickened L, and that the eye dam- 
age caused by the unthickened L was more severe 
than that caused by thickened 

The tactical value of producing L blisters on hu- 
man skin is thrown into very serious doubt by recent 
Canadian experiments in which observers clad in 
battle dress and shirts over long-limbed underwear 
and wearing respirators and steel helmets were ex- 
posed to airplane spray of L to which had been added 
0.55 per cent of thickener. The temperature was 
75 F with relative humidity = 39 per cent, and the 
contamination density was 0.7 to 5.4 g/m^. The 
drops varied between 1.3 and 5.6 mm in diameter. 
Of 30 men hit by the spray, 20 developed lesions 
which in 7 cases were numerous and prominent but 
in other cases were trivial. It was noted that the in- 
dividual lesions produced were discrete and circum- 
scribed in contrast to the diffuseness of the typical 
lesion produced by H spray. After 9 days of compara- 
tively strenuous exercise, none of the observers was 


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ARSENICALS 


in such condition that he could not carry out military 
duties, and in no case had secondary infection de- 
veloped. It was concluded that the casualty-produc- 
ing propensities of H spray are definitely greater 
than those of L spray. 

Protection against Lewisite 

Lewisite Vapor. The median detectable concen- 
tration of L vapor by odor is stated to be 0.014 to 
0.023 mg/1. However, the irritating effect of the gas 
on the eyes and respiratory passages is noticeable at 
far lower concentrations, variously estimated as 
0.008 mg/1 and as 0.006 mg/l.^^'^ On the basis of 
these figures, a concentration of 0.006 mg/1 should 
certainly warn troops of the presence of gas and 
should lead to masking or to withdrawal from the 
toxic atmosphere. The service respirator gives en- 
tirely adequate protection to the eyes and respiratory 
tract against the effects of L vapor. Even in the ab- 
sence of the respirator, serious eye effects from L 
vapor are unlikely to occur in conscious men since 
the immediate response of the eye to L vapor is lacri- 
mation and blepharospasm, both of which protect 
against further exposure. 

Ordinary clothing affords considerable protection 
against L vapor. It has been estimated that a 
single layer of dry cloth would protect against ap- 
proximately three times the concentration of L that 
would produce a reaction on bare skin. The British 
estimated that a Ct of 3. 0-4.0 mg min/1 would be 
required to produce an effect under a single layer of 
dry serge. In another report, it was found that the 
penetration of cloth by L vapor decreases with in- 
creasing humidity, and it was suggested that the 
reason lies in reaction of L with moisture on the 
fibers of the cloth. Complete protection against L 
vapor was afforded by ordinary dungaree shirt ma- 
terial, S-330 ointment, and CC-2 impregnated cloth 
up to at least Ct 3.3 (analytical) under exposure con- 
ditions of 90 F and 65 per cent relative humidity 
with 4 hours wear of the clothing after exposure. 

Wet clothing is much more effective in protecting 
against L vapor than dry clothing. It has been esti- 
mated that 100 times the concentration of L that 
would produce an effect on bare skin would be re- 
quired to penetrate a single layer of wet cloth. In 
fact the British state that L vapor will not burn 
through wet clothing. 

Liquid Lewisite 

Liquid lewisite in the eyes is capable of causing se- 
vere damage. However, complete protection against 


liquid L is afforded to the eyes by wearing the respi- 
rator or the eye shield or even by closing the eyes. 

Liquid L will penetrate ordinary dry clothing, a 
drop of 2.5 mg (1.5 mm in diameter) generally caus- 
ing vesication through dry service clothing in temper- 
ate climates. Under tropical conditions a 0.4-mg 
drop (0.77 mm in diameter) may produce vesication 

through light dry clothing. ^^4 

Wet clothing protects against liquid L by forming 
the insoluble and nonvolatile L-oxide before the 
agent can penetrate to the skin.^^^ CC-2 impregnated 
clothing offers more protection against liquid L than 
does unimpregnated dry clothing, although 5.7 mg 
of L produced vesication through a single layer of 
CC-2 impregnated cloth,^^^ indicating that the pro- 
tection afforded against L is less than that against H. 

Comparison with Mustard 

The toxicity of L vapor and H vapor by inhalation 
are of the same order of magnitude. However, to pro- 
duce systemic effects through the skin, eye damages, 
or skin vesication, significantly higher Ct’s are re- 
quired for L than for H. Because of the rapid de- 
struction of L liquid and vapor in contact with 
moisture or with an alkaline environment the requi- 
site Ct’s for L would be extremely difficult to attain 
in the field. Further, L vapor, unlike H vapor, is not 
insidious but gives adequate warning of its presence 
by irritation of the eyes and respiratory passages. 

Liquid L is more vesicant than liquid H but the 
burns from L do not incapacitate men to the same 
extent as do burns from H,^^^ and the L burns heal 
more rapidly and are less painful than those from H. 
Liquid L on the skin or in the eyes produces an im- 
mediate stinging sensation which warns of its pres- 
ence, whereas mustard is nonirritating at the time of 
application. 

Mustard penetrates ordinary clothing much more 
readily than does L, and, since H is more stable than 
L, is a better choice both for terrain contamination 
and vapor return. 

Mixtures of H and L have been suggested but have 
no advantage over H used alone except with respect 
to lower freezing point. 

Therapy 

In 1941, the discovery of a powerful therapeutic 
agent against L and other arsenicals was an- 
nounced. This substance, 2, 3-dime reap topropanol- 
1, variously known by the code letters BAL and 
DTH, will not only destroy arsenicals on contact, 
but is capable of minimizing the damage from liquid 


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PHYSIOLOGICAL SECTION 


95 


arsenicals in the eyes if applied from 1 to 10 minutes 
after exposure, and from liquid arsenicals on the skin 
if applied up to 1 hour after contamination. 

A discussion of BAL is beyond the scope of this 
report except to say that an ointment containing 
BAL was available for issue to United States soldiers. 
This ointment was suitable for application to the 
skin or eyes and placed in the hands of the soldier a 
method of self-help for minimizing the effects of con- 
tamination from liquid arsenical agents. Prepara- 
tions of BAL were available to physicians for paren- 
teral administration and are effective in combatting 
systemic intoxication from arsenicals. 

Summary 

By the end of the World War II, the toxicology of 
L had been worked out to the point where the dosages 
required to produce casualties or death in human be- 
ings were known with a degree of approximation that 
is probably sufficient for military purposes. 

Field tests, however, showed little promise of at- 
taining the requisite dosages of L vapor with any 
reasonable expenditure of munitions. The use of 
liquid L for gross contamination of personnel seems 
feasible only when the agent is dispersed as low- 
altitude airplane spray, and the effects produced on 
contaminated personnel are so inferior to those pro- 
duced by mustard as to create strong prejudice 
against the use of L. 

Since the powerful antiarsenical agent, BAL, avail- 
able to Britain and the United States in World 
War II, will be available to all in the future, there 
seems to be little likelihood that there will ever be 
any incentive for the use of L as a chemical warfare 
agent. 

7.3.2 Chlorarsine Derivatives Other 
Than Lewisite 

Lethal Agents 

In the Spring of 1918, ethyldichlorarsine (ED) was 
used by the Germans as a skin and lung irritant suit- 
able for gassing operations to be followed by infantry 
assaults.^^^'^^® There is no mention in Allied official 
records of casualties attributed directly to ED, but 
the Germans held the compound in high regard. The 
United States Chemical Warfare Service investigated 
methyldichlorarsine (MD) during the latter half of 
1918 but the compound was not used in battle. 

In 1939, the results of a preliminary investigation 
by the Chemical Warfare Service revealed a lack 
of sufficient data for making a definite decision as to 


the value of ED as a military agent, but stated that 
“the present available data indicate sufficient poten- 
tial value to warrant further study and develop- 
ment.” Accordingly, the National Defense Research 
Committee [NDRC] was asked to screen the arseni- 
cals for toxicity and stability in order to determine 
whether any members of the group were sufficiently 
promising to warrant further study or development 
as chemical warfare agents. A number of chlorarsine 
derivatives were prepared and were studied for toxic- 
ity at the University of Chicago Toxicity Labora- 
tory [UCTL]. 

Physiological Action. The toxic chlorarsine deriva- 
tives produce effects which are qualitatively similar 
to those produced by L (q.v.) but which differ in 
degree. Thus, they are all irritant to the respiratory 
tract and produce lung injury on sufficient exposure. 
The vapors are irritating to the eyes and the liquids 
may produce serious eye lesions. The absorption of 
either vapor or liquid through the skin in adequate 
dosage may lead to systemic intoxication or death. 
Local skin damage leading to vesication in man is 
usually produced by sufficient exposure to the vapor 
or by contact with the liquid. 

Vapor Toxicity. The chlorarsines originally 
screened for vapor toxicity at the UCTL are listed 
in Table 6, which shows the results of tests against 


Table 6. Toxicity of vapor of chlorarsines for mice. All 
figures for LCCOso are in mg min/1 (nominal). 


Compound 

L{Ct) — (Mouse) 

Lewisite, isomer I 

L(C05o = 2.8 

Lewisite, isomer II 

Plant run lewisite, isomer I 

L(C05o = 2.8 

Phenyldichlorarsine 

L(C05o = 3.7 

/3-Chloroethyldichlorarsine 

L(C09o 13. 

/3-Methoxyethyldichlorarsine 

unstable 

/3-Ethoxyethyldichlorarsine 

/3-Chloromethoxypropyldichlor- 

unstable 

arsine 

(No deaths at = 8.7) 

Allyl phenylchlorarsine 
Phenyl(/3-chlorovinyl)chlor- 

(No deaths at = 24.44) 

arsine 

L{Ct)io ~ 1. 

Isoamyldichlorarsine 

L(C06o 2. 

sec-Butyldichlorarsine 

12. 

6zs( Chloromethyl )chlorarsine 

L{Ct)io 4.5 

Chloromethyldichlorarsine 

(No deaths at Ct = 43.5) 

4-Penten3ddichlorarsine 

L(Ct)zz ^ 3.7 

Amyldichlorarsine 

LiCtU = 2.5 

Butyldichlorarsine 

L(C05o 3.5 

Ethyldichlorarsine 

L(C05o 3.5 

)8-Furyldichlorarsine 

(No deaths at Ct = 2.3) 

Heptyldichlorarsine 

UCtU ~ 13.1 

/3-Methylbutyldichlorarsine 

unstable 

Hexyldichlorarsine 

L{Ct)^Q 3. 

Dimethylchlorarsine 

L{Ct)zo 10. 


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ARSENICALS 


mice by total exposure for 10 minutes. On the basis 
of the information listed in Table 6 and information 
from the Chemical Warfare Service on butyl- 

dichlorarsine/^® amyldichlorarsine/^^ and isoamyl- 
dichlorarsine/^^ a more detailed investigation was 
made of the toxicities toward mice (by total expo- 
sure) of the vapors of the alkyldichlorarsines from 
methyl- through hexyl-."*^ In order to avoid errors 
known to result from different degrees of humidifica- 
tion of the animal’s fur, the mice were exposed for 
1 hour to a relative humidity of 20-30 per cent before 
exposure to the toxic arsenical. The dichlorarsines 
were vaporized with dry nitrogen at 25-30 C and 
were passed through the 4-1 glass chamber at 11.2 
1pm. The relative humidity of the gases in the cham- 
ber did not exceed 8 per cent. 

The vapor toxicities of the alkyldichlorarsines are 
given in Table 7, together with the toxicity of phenyl- 
dichlorarsine (PD) and of L for purposes of com- 
parison. 


Table 7. Toxicity of vapor of dichlorarsines for mice. 

All figures are L(C05o in mg min/1. 

Exposure time = 10 min; observation period = 10 days. 


Agent 

Total exposure 

Methyldichlorarsine 

2.7 (anal.)« 

Ethyldichlorarsine 

1.555 (anal. )« 

Ethyldichlorarsine 

3.4 (nom.)i29 

Propyldichl orarsine 

1.4 (anal.)^3 

Butyldichlorarsine 

1.8 (anal.)^^ 

Butyldichlorarsine 

3.7 (nom.yao 

Amyldichlorarsine 

1.4 (anal.)^® 

Amyldichlorarsine 

3.7 (nom.ys^ 

Isoamyldichlorarsine 

3.7 (nom.y57 

Hexyldichlorarsine 

1.5 (anal.)^3 

Phenyldichlorarsine 

3.4(nom.)27; 3.3 (nom.)ii9 

Lewisite 

1.5 (anal.)"*® 

Lewisite 

2.8 (nom.F 


Examination of the data of Table 7 leads to the 
conclusion that all of the dichlorarsines tested, with 
the possible exception of MD, have essentially the 
same toxicity toward mice. 

Fifty-three dihaloarsines were tested at the UCTL 
and the conclusion reached that the members of 
the series vary in toxicity up to a maximum in the 
group that contains L, ED, and the homologous 
straight chain aliphatic dichlorarsines. Data have 
also been obtained for a number of monohalogenated 
arsines,®* but none of these compounds are superior 
to L. 

References to the vapor toxicities of other halo- 
genated arsines will be found in Table 9. 


The toxicity of several dichlorarsines when applied 
to the skin (shaved) of mice is shown in Table 8. 


Table 8. Percutaneous toxicity of arsenicals for mice.^^ 


Compound 

Dose 

mg 

No. of 
mice 

Per cent 
mortality 
10-day 
period 

Comparison 

with 

lewisite 

L (plant run) 

0.1 

10 

0 



0.3 

10 

50 



0.5 

10 

100 


ED 

0.1 

4 

0 



0.5 

4 

25 



1.0 

4 

25 


N-Butyldichlor- 

0.5 

10 

10 


arsine 

.1.0 

10 

30 

<i L 

iS-Methylbutyl- 

0.5 

4 

25 


dichlorarsine 

1.0 

4 

100 

~Vl 

N-Amyldichlor- 

0.1 

7 

14 


arsine 

0.3 

10 

80 

= L 


0.5 

10 

100 


Hexyldichlor- 

0.1 

4 

0 


arsine 

0.5 

4 

50 



1.0 

4 

50 

-Vl 

Heptyldichlor- 

0.1 

4 

0 


arsine 

0.5 

4 

0 

-Vl 


1.0 

4 

50 


PD 

0.1 

10 

20 



0.3 

10 

30 

= L 


0.5 

10 

100 



These data show that none of the dichlorarsines 
tested are more toxic than L and that only amyldi- 
chlorarsine and PD equal L in systemic toxicity. 

Thirty-five dihalogenated arsines and thirteen 
monohalogenated arsines were examined for vesi- 
cancy at the UCTL ®* without revealing any vesicant 
superior to lewisite. 

In general, the dichlorarsines are better vesicants 
than the monochlorarsines,^® and the simple alkyl- 
dichlorarsines compare favorably with L in respect 
to “absolute” vesicancy, i.e., when evaporation of 
the liquid from the skin is prevented by covering. 

The introduction of a single chlorine atom on the 
terminal carbon of a normal aliphatic substituent in 
a dichlorarsine or the use of branched chain sub- 
stituent groups results in loss of vesicant potency.^^ 
Thus, ED is a more potent vesicant than L when 
evaporation from the skin is prevented, and amyl- 
dichlorarsine is a better vesicant than isoamyldi- 
chlorarsine.2'^'^®^ 

Eye Effects 

The vapors of the chlorarsines are generally irri- 
tating to the eyes, leading to lacrimation and bleph- 


SECRET 


PHYSIOLOGICAL SECTION 


97 


arospasm which protect against further damage. 
Liquid MD produces a lesion in the rabbit eye which 
is less severe than one caused by Liquid ED 

produces a lesion in the rabbit eye which is compa- 
rable in severity to that caused by BAL is 

effective in the prevention of eye damage from 
either MD or ® 

Assessment of the Military Value of Chlorarsines 
Other than L. Of all the chlorarsines studied, only 
MD, ED, PD, butyldichlorarsine, and the amyldi- 
chlorarsines approach L in toxicity and vesicant 
potenc 3 ^ Of these, butyldichlorarsine is too un- 
stable and the amyldichlorarsines too difficult to 
prepare to be considered as chemical warfare 
agents. 

Thus, after an exhaustive examination of many 
compounds, it appears that the best of the chlor- 
arsines other than L are those which were used (ED 
and PD) or considered for use (MD) in World War I. 
The status of MD, ED, and PD as military agents 
has recently been reviewed with the following 
results : 

1. MD. The vapor is so irritating that it is easily 
detected at low concentrations and would lead to 
prompt masking. The vapor is easily hydrolyzed and 
the dosage required for skin vesicancy so high that 
there is no hope of obtaining vesicant dosages of 
vapor in the field. The skin and eye effects of the 
liquid are not so damaging as those produced by L. 

2. ED. Ethyldichlorarsine is somewhat superior 
to MD but is inferior to L as a casualty agent. 

3. PD. The vesicancy, systemic toxicity, and 
toxicity by inhalation of PD are equal to those of L, 
but PD penetrates clothing less effectively than L 
and the volatility of PD is so low that casualties from 
exposure to the vapor are hardly to be expected in 
the field. Like MD and ED, Pi!) is easily hydro- 
lyzed. 

In view of these facts, it appears that the best of 
the chlorarsines are inferior to L and, since L itself 
does not appear to have any future as a chemical war- 
fare agent, it can be assumed that the other chlor- 
arsines will not be considered further as military 
agents for casualty effect. It is interesting to note, 
however, that the Allies captured a considerable 
number of German artillery shells charged with a 
mixture of mustard and PD. Whether this indicates 
that the Germans held a higher opinion of the effec- 
tiveness of PD than the Allies or the mixture was 
dictated by other considerations is not clear at the 
present time. 


7.3.3 Arsine and Nonhalogenated Arsine 
Derivatives 

Arsine 

During World War I, the Allies did considerable 
exploratory work on the potentialities of arsine as a 
chemical warfare agent. In 1919 it was stated: 

During the war many suggestions were made that arsine 
should be used. The popular plan was to use magnesium arse- 
nide which would hydrolyze in moist air, setting free arsine. 
The experiments made by the Research Division showed that 
the hydrolysis does not take place rapidly enough under or- 
dinary conditions to give an efficient concentration of arsine. 
At the time of the armistice experiments were still under w ay 
to determine whether this material could be used effectively 
in the rain. While the use of magnesium amenide or of any 
arsenide w'as not very promising, there seemed to be a distinct 
possibility of using liquid arsine ... If arsine is to be used in 
w’arfare, it seems probable that it must be used as liquid. 

In 1939, the available data concerning arsine as a 
potential chemical warfare agent were summarized 
with the conclusion that its value would depend on 
whether the canister of the gas mask would afford 
sufficient protection against it under all conditions to 
which the canister might be exposed. 

It was recognized that arsine might be useful as a 
casualty agent aside from its lethal effects and ac- 
cordingly studies of the toxicity and suitability of the 
compound for chemical warfare use were reinvesti- 
gated by both the Americans and the British. 

Physiological Action. The physiological action of 
arsine has been well summarized in the open liter- 
ature.^^® 

In vitro studies have shown that arsine is oxidized 
aerobically in aqueous solution, and that this oxida- 
tion is catalyzed by hemoglobin In the presence 
of arsine and oxygen, however, the hemoglobin un- 
dergoes destruction forming a number of compounds 
including methemoglobin, and a tetrapyrrolic com- 
pound whose spectrum resembles that of sulf methe- 
moglobin. During the reaction of arsine with 
hemoglobin about 40 per cent of the arsine taken up 
is held in a nondialyzable form, while the remainder 
is mostly arsenite with a small amount of arsenate. 
There'is no reaction between arsine and hemoglobin 
under strictly anaerobic conditions.^®^'" 

Arsine is a strong hemolytic agent in vivo; and 
in vitro under aerobic conditions only.^®'*’" In view of 
the known oxidation products of arsine, experiments 
were carried out to determine whether the hemolytic 
effects of arsine were due to arsenite or arsenate 
rather than to arsine per se, but with negative re- 
sults.®^ 


SECRET 


98 


ARSENICALS 


The action of arsine on tissue slices has been stud- 
ied and compared with that of arsenite, with the con- 
clusion that the effect of arsine in reducing the 
oxygen uptake of kidney slices is similar to that of 
arsenite. BAL protects kidney slices against the 
effects of arsine but not of arsenite.®^ The action of 
arsine on liver slices is not identical with that of 
arsenite since the toxicity of arsine increases more 
rapidly with increasing concentration, and liver 
slices treated with arsine change color, suggesting a 
reaction with heme compounds that does not occur 
with arsenite-treated liver slices. 

Toxicity. Available data on the toxicity of arsine 
by inhalation have been summarized. The data 
cited are quite variable both for exposures of a given 
species and for different species. The LC50 for mice 
has been determined as of the order of 0.250 mg/1 for 
a 10-minute exposure; but studies at the 

UCTL^^ resulted in a figure of 0.520 ± 0.100 mg/1 
(analytical), with no apparent explanation of the 
discrepancy. 

There do not appear to be any satisfactory data 
for the LCso for dogs with 10-minute exposure, but 
0.35 mg/1 for a 30-minute exposure is said to be the 
LCbo,^^^ and lethal concentrations for various ex- 
posure periods have been compiled. Rabbits are 
apparently less susceptible to arsine than mice, the 
Z/C50 for 10-minute exposure being estimated to lie 
between 0.65 and 0.96 mg/1.^^* No satisfactory LC50 
has been reported for cats, but 0.80 mg/1 for 10 
minutes caused the death of 3/4 eats within 18 hours 
(G-2 Report No. 1322 216)^ whereas cats exposed to 
4.1 mg/1 for 1 minute did not die.^^ 

The LC50 for rats on 10-minute exposure is of the 
same order as that for mice, being between 0.39 and 
0.66 mg/1 (G-2 Report No. 1322 2^®). The LC50 for 
goats on 10-minute exposure is estimated as being 
between 1.0 and 2.2 mg/1 (G-2 Report No. 1322 
Four of five monkeys died after exposure to 0.45 mg/1 
for 15 minutes. 

No data exist for the LC50 for man, but the mini- 
mum disabling concentration has been estimated as 
2.0 mg/1 for 2 minutes or 0.2 mg/1 for 30 minutes. 
Henderson and Haggard state that exposure to a 
concentration of arsine between 0.051 and 0.191 mg/1 
would be dangerous after 30 minutes, whereas ex- 
posure to 0.798 mg/1 would be fatal after 30 min- 
utes.^2* British estimates based on the assumption 
that 2 mg/kg of arsine would be fatal to man put the 
casualty-producing Ct at 14 mg min/1 for a man at 
rest and at 4.66 mg min/1 for a man working; and the 


fatal Ct at 28 mg min/1 and 93 mg min/1 for a resting 
man and working man respectively.^^^ Early British 
results indicated that for the effect of arsine on mice 
the product CH rather than Ct was a constant, but 
later investigation showed that for concentrations 
greater than 0.5 mg/1, Ct was constant, whereas for 
concentrations less than 0.5 mg/1, CH was constant.^®^^ 

On the grounds that the incapacitation of troops 
may be as valuable as their death in most military 
situations, and that the incapacitating dose of an 
agent may be quite different from the lethal dose, 
studies were carried out on rabbits to examine the 
possibilities.^^* The results indicated that exposure of 
rabbits to 0.05 mg/1 for 10 minutes caused significant 
changes in the oxygen-carrying capacity of their 
blood, but that the effect was transient. After 10- 
minute exposure to concentrations between 0.13 and 
0.20 mg/1 the rabbits were no longer able to maintain 
a relatively high red blood cell count, and the de- 
crease in oxygen-carrying capacity of the blood was 
severe in about half of the animals, whereas with 
10-minute exposures to concentrations between 
0.234 and 0.40 mg/1 a marked decrease in hemoglobin 
was invariably noted. A similar decrease in the hemo- 
globin content of human blood might be expected to 
cause severe but sublethal casualties. 

Therapy. Dithiol compounds are effective in the 
treatment of arsine poisoning, although BAL-ethyl 
ether (2, 3-dime rcaptopropyl ethyl ether) is more 
effective than BAL itself.^*® Since BAL-ethyl ether 
is tolerated by human beings in therapeutic dosages 
without toxic symptoms, the compound appears to 
be suitable for the treatment of arsine poisoning in 
man. 

Assessment of Value as a Chemical Warfare Agent. 
The conclusion of the United States Chemical 
Warfare Service in 1939 was that the value of arsine 
as a chemical warfare agent would depend on the 
question of canister protection. The British in 1941 
concluded that the only potential method for the 
liberation of arsine would be by high-capacity bombs 
and that the only possible advantage over gases of 
the phosgene type would be that its detection at low 
concentration is more difficult. In order to utilize low 
concentrations of arsine, however, exposure must be 
prolonged and this is very difficult to obtain short of 
excessive effort, so that on the whole arsine should 
not merit any particular consideration as an offen- 
sive weapon, provided respirator protection is ade- 
quate.^*® 

The question of canister protection against arsine 


SECRET 


PHYSIOLOGICAL SECTION 


99 


has been summarized as follows: “At one time arsine 
was thought to be a \^ery promising war gas because 
it penetrates humidified unimpregnated or copper 
oxide impregnated charcoal very readily. With the 
introduction of sih^er impregnation, however, the 
protection against arsine was made almost compa- 
rable to phosgene. ...” 

The weight of arsine that would have to be ex- 
pended to produce a lethal concentration is theoreti- 
cally about 10 times as great as the weight of phos- 


gene required for the same purpose. Since, in ad- 
dition, modern respirators give adequate protection 
against it, arsine shows little promise in chemical 
warfare. 

Nonhalogen ATED Arsine Derivatives 

A number of tertiary arsine derivatives have been 
examined for toxicity. Data for 51 such compounds 
were obtained by the UCTL,®® and reference to these 
and to other tertiary arsines are listed in Table 9. 


Table 9. Arsenical compounds examined as candidate chemical warfare agents. 

The compounds in Table 9 are arranged in the following categories: 

1. Derivatives of arsine. 

2. Derivatives of primary arsines. 

3. Derivatives of secondary arsines. 

4. Tertiary arsines. 

5. Quaternary arsenic derivatives. 

6. Arsenic analogs of hydrazine. 

7. Derivatives of arsenic oxides, sulfides, and amines. 

8. Halogen and oxygen derivatives of tertiary arsines. 

9. Derivatives of arsenic, arsonic, and arsinic acids. 

10. Arsenic derivatives of uncertain constitution. 

British reports describing the examination of compounds marked with an asterisk are not all available. 
Centigrade scale is used throughout the table. 


Reference 

to 


Physical properties 


Reference to 
toxicity 


Compound 

synthesis 

Property 

Reference 

data 

Derivatives of arsine 

1. Calcium arsenide 

311 


2.5 

311 

311 

2. Arsine 

296b, 311 


1.44 

296b 

23, 311 



mp 

116.1-116.0° 

296b 

. . . 



bp 

62.8° 

296b 

. . . 

3. Arsenic trifluoride 

311,333 


2.6659 

298a 

68, 311 



mp 

8.5° 

298a 

. . - 



bp 

60.4° 

298a 

. . . 



vol 

152 

311 

• • • 

4. Arsenic trichloride* 



1.6009 

311 

252 




2.163 

244 

» • • 



mp 

13° 

311 

. • . 



bp760 

129-130° 

244 

. . • 



VoPO 

84 

311 

• • • 

5. Arsenic trichloride — dioxane complex* 


. . . 



227 

6. Arsenic trichloride — thioxane complex* 


. . . 



227 

7. Arsenic pentafluoride 

342 

mp 

80.4° 

298a 

• , , 

' 

. . . 

bp 

52.8° 

298a 

• • • 

Derivatives of primary arsines 

8. Methylarsine 

5 

bp 

2° 

5 


9. Methyldifluorarsine* » 

296c, 298a 

d 

1.9725 

298a 

298a 


. . . 

mp 

30° 

296c, 298a 

. . . 



bp 

76° 

296c, 298a 


10. Methyldichlorarsine* 

32, 290j,311 

no"® 

1.5588 

32 

27, 43, 68, 




1.8358 

32 

311 


. . . 

mp 

42.5° 

32 



. . . 

bp760 

132.5° 

32 



. . . 

voP“ 

74.4 

311,70 


1 1 . Chloromethyldichlorarsine 

47 

bpi“ 

68.3 

53° 

47 

27,’ 68 



vol 

135 

27 



SECRET 


100 


ARSENICALS 



Table 9 {Continued). 




Compound 

Reference 

to 

synthesis 

Physical properties 
Property Reference 

Reference to 
toxicity 
data 

12. 2-Chlorovinyldifluorarsine* 

113, 180, 296c 


1.97 

180 

121 



mp 

26° 

180 




bpl4.5 

43.5° 

296c 




bp 

105-110° 

180 




voP® 

31.77 

180 


13. 2-Chlorovinyldichlorarsine* 

See Bibli- 

nxi^ 

1.6073 

43 

See Bibli- 

Lewisite (isomer 1) 

ography 


1.879 

27 

ography 



mp 

2.4° 

27 




bp‘° 

75° 

43 




bp760 

190° 

27 




voP“ 

2.3 

311 




VOpO 

4.47 

70 


Lewisite (isomer 2) 

See Bibli- 


1.5900 

27 

See Bibli- 

ography 


1.8681 

27 

ography 



bp^® 

62.8° 

27 




bp760 

150.2° 

27 


14. 2-Chlorovinyldichlorarsine-dioxane complex* 





227 

15. 2-Chlorovinyldibromoarsine* 

231 

bpl7-18 

106-107° 

231 

231 

16. 2-Bromovinyldibromoarsine* 

231 

bp^* 

132-137° 

231 

231 

17. 2,2-Dichlorovinyldichlorarsine* 

311 




311 

18. Ethylarsine 

39 


1.217 

39 

68 



bp735 

35-36° 

39 


19. Ethyldifluoroarsine* 

112, 296c 

d 

1.743 

296c 

117 



mp 

38.7° 

296c 




bp 

94.3° 

296c 


20. Ethyldichlorarsine* (ED) 

5, 32, 48, 


1.5588 

311 

27, 43, 68, 

58, 311 


1.6595 

32 

79, 311 



bp735 

153-155° 

5 




voP*^ 

21.9 

127 




vopo 

30.2 

70 


21. Ethyldibromoarsine 

58 


1.6405 

58 

68, 79 




2.403 

58 




bp^® 

87-88° 

58 




voP® 

5.72 

70 


22. 2-Chloroethyldichlorarsine* 

1, 111, 114 

bpi® 

99.8-100° 

1 

27, 79,116 

23. 2-Hydroxyethyldichlorarsine* 





227 

24. 2-Methoxyethyldichlorarsine 

1 


1.693 

1 

27, 79 



bp® 

94-95° 

1 




bp^® 

102-103° 

1 


25. 2-Ethoxyethyldichlorarsine 

1 

d2o 

1.605 

1 

27, 79 



bp‘® 

95-97° 

1 


26. Allyldichlorarsine 

1, 32, 58, 

riD^® 

1.5702 

1 



105 


1.6294 

32 




bp^® 

42° 

32 

68, 121, 

27. 3-Chlorallyldichlorarsine 

301c 

bp^® 

104-105° 

301c 

79, 120 

227 

28. Propyldichlorarsine* 

32 


1:5297 

32 

43, 68, 79 



d2o 

1.5380 

32 




mp 

28.2° 

32 




bp7® 

99° 

32 




bp7®0 

175.3° 

32 




voP® 

12.4 

70 


29. Propyldibromoarsine* 





227 

30. Propyldicyanoarsine 

39 

mp 

82-86° 

39 

68, 79 

31. Isopropyldichlorarsine* 





227 

32. 3-Chloropropyldichlorarsine* 

311 




311 

33. 3-Chloromethoxypropyldichlorarsine 

5 

bp® 

136-137° 

5 

27, 79 


SECRET 


PHYSIOLOGICAL SECTION 


101 


Table 9 {Continued). 


Compound 

Reference 

to 

synthesis 


Physical properties 
Property Reference 

Reference to 
toxicity 
data 

34. 2-Chloro-3-(2-chloroethylthio)-l-butenyldichlor- 

arsine* 





227 

35. Butyldichlorarsine* 

1,32, 130 


1.4664 

32 

27, 43, 79, 



bp760 

194° 

32 

121, 130 



vops 

6.3 

130 


36. Butyldibromoarsine* 





227 

37. Butyldicyanoarsine 

58 

mp 

61-63° 

58 

68, 79 

38. sec-Butyldichlorarsine* 

32 


1.5245 

32 

27, 68, 79 



d2o 

1.4128 

32 




bp760 

182° 

32 




bp^-3 

39° 

32 


39. 2(or 4)-Chloro-3-methyl-l,3 (or l,2)-butadienyl- 

dichlorarsine* 





227 

40. 4-Pentenyidichlorarsine 

32 


1.5698 

32 

27, 68, 79 



d26 

1.453 

32 




bp3.5 

102.5-105.5° 

32 




bp26 

111-114° 

32 




vol 

0.12 

27 


4 1 . 2-C hloro- 1 -pentenyldichlorarsine 

38 

bp26 

130-133° 

38 

68, 79 

42. Amylarsine 

58 

bp730 

125-127° 

58 

68 

43. Amyldichlorarsine* 

28, 32, 58 


1.5177 

32 

27, 43, 157, 



d20 

1.4035 

32 

79 



bp3® 

118° 

32 




bp760 

213° 

32 


44. Amlydibromoarsine 

39 


1.5760 

39 

68, 79 




1.8804 

39 




bp^* 

125.5-127° 

39 




bp^®^ 

248° 

39 




vol 

0.399 

70 


45. Amyldicyanoarsine 

58 

mp 

69-69.5° 

58 

68, 79 

46. Isoamyldichlorarsine 

28, 32 

nD25 

1.5157 

32 

68, 79, 157 



d28 

1.3904 

32 




bp^ 

72.5-74° 

32 


47. 2-Methylbutyldichlorarsine 

32 

riD^® 

1.5183 

32 

27 



d26 

1.4302 

32 




bp2i 

101-105° 

32 


48. Hexyldichlorarsine 

32 

riD^® 

1.5122 

32 

43, 68, 79 



d27 

1.352 

32 




bp28 

125-127° 

32 


49. Hexyldicyanoarsine 

58 

mp 

67.8-69.8° 

58 

68 

50. Heptyldichlorarsine 

32, 58 


1.5102 

32 

27, 68, 79 



d27 

1.3206 

32 




bp^'‘ 

130-131.5° 

32 


51. Phenylarsine 

58 


1.5967 

58 

68, 79 



d26 

1.524 

58 




bp®® 

85-88° 

58 




bp®2 

80-83° 

58 


52. Phenyldifluoroarsine* 

109, 296c 

mp 

42° 

296c 

121, 252 

53. Phenyldichlorarsine (PD)* 

58, 311 


1.6332 

58 

27, 79, 252 



d2® 

1.650 

58 

311 



bp23 

137-140° 

58 




bp 

252-254° 

58 




voP® 

0.404 

311 




voP® 

0.280 

70 


54. Phenyldibromoarsine* 





252 

55. Phenyldiiodoarsine* 





252 

56. o-Chlorophenyldichlorarsine* 

58, 301e 


1.6380 

58 

68, 79 



d®! 

1.747 

58 




mp 

44-45° 

58 




bp2® 

163.5-165° 

58 



SECRET 


102 


ARSENICALS 


Table 9 (Continued). 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Reference to 
toxicity 
data 

57. 

7/i-Chlorophenyldichlorarsine* 

311 

mp 

4° 

311 

311 




bp* 

124° 

311 





bp^* 

154° 

311 


58. 

p-Chlorophenyldichlorarsine* 

311 




311 

59. 

o-Bromophenyldichlorarsine* 





227 

60. 

??i-Bromophenyldichlorarsine* 

311 

mp 

8-10° 

311 

311 




bp^^ 

162° 

311 


61. 

p-Bromophenyldichlorarsine * 

311 

mp 

11.8° 

311 

311 




bp* 

156° 

311 


62. 

o-Nitrophenyldichlorarsine* 

58, 311 

mp 

49° 

58 

49, 79, 311 

63. 

m-N itrophenyldichlorarsine * 

5, 58, 311 

mp 

55° 

5 

49, 68, 79, 







311 

64. 

p-N it ropheny Idi chlorarsine * 

5 

mp 

54-55° 

5 

49, 79 




bp2 

170° 

5 


65. 

2,4-Dinitrophenyldichlorarsine 

58 

mp 

69-70.5° 

58 

49, 79 

66. 

o-Hy droxy phenyldichlorarsine * 

311 

mp 

77° 

311 

311 

67. 

o-Methoxyphenyldichlorarsine * 





227 

68. 

p-Methoxj’^phenyldichlorarsine* 





227 

69. 

3,5-Dinitro-4-ethoxyphenyldichlorarsine 

58 

mp 

81-82.3° 

58 

68, 79 

70. 

p-2-Chloroethylt hiophenyidichlorarsine * 

5 

bpO.004 

150° 

283 

283, 291g 




bpO.25 

186-193° 

5 


71. 

2-Phenoxy phenyldichlorarsine * 





227 

72. 

2-( 2 '-Chlorophenoxy )pheny Idichlorarsine * 





227 

73. 

2-( 3 '-Chlorophenoxy )phenyldichlorarsine * 





227 

74. 

2-( 4 '-Chlorophenoxy )phenyldichlorarsine * 





227 

75. 

w-N -Chloroacetylaminophenyldichlorarsine * 

307q 

mp 

105° 

307q 

227 

76. 

N - Acetyl-N -phenyl-p-aminophenyldichlorarsine * 





227 

77. 

p-Tolylarsine 





68, 79 

78. 

o-Tolyldichlorarsine * 





227 

79. 

2-Methyl-6-nitrophenyldibromoarsine* 





227 

80. 

m-Trifluoromethylphenyldichlorarsine 

84h 




68 

81. 

p-Toly Idichlorarsine * 





227 

82. 

2-Chloro-4-methylphenyldichlorarsine* 





227 

83. 

2-Bromo-4-met hylphenyldichlorarsine * 





227 

84. 

3,5-Dinitro-4-methylphenyldichlorarsine 

58 

mp 

126-127.5° 

58 

68, 79 

85. 

o-Dichlorarsinobenzoyl chloride* 





227 

86. 

o-Dichlorarsinobenzoic acid* 

58 

mp 

159-169° 

58 

68, 79 

87. 

Benzyldichlorarsine 

311 

bp^” 

175° 

311 

311 

88. 

p-Acetylphenyldichlorarsine * 





227 

89. 

m-Chloroacet ylphenyldi chlorarsine * 

5 

bpis 

215-218° 

5 

227 

90. 

p-Chloroacetylphenyldichlorarsine* 





227 

91. 

p-Xenyldichlorarsine * 





227 

92. 

2-( 4-Chloroacetylpheny 1 )phenyldich lorarsine * 





227 

93. 

2-Fluorenedich lorarsine * 





227 

94. 

2-Fluorenonedichlorarsine* 





227 

95. 

o-Benzoylphenyldichlorarsine * 





227 

96. 

2,2 '-bis{ Dichloroarsino )stilbene * 





227 

97. 

2- N aphthyldichlorarsine 

73 

mp 

74.6-75.1° 

73 

68, 79 

98. 

2-Furyldichlorarsine* 

1, 25, 301d, 


1.6092 

25 

27, 311 



311 









1.797 

25 





bpi-2 

85-98° 

25 


99. 

2-Thienyldichlorarsine * 

311 

bp^^ 

118-122° 

311 

311 

100. 

3-Pyridy Idichlorarsine hydrochloride * 

39 

mp 

229-235° 

39 

68 

101. 

Quinolyl-8-dichlorarsine 

84h 





102. 

8-Methylquinolyl-5-dichlorarsine hydrochloride 

84g 

mp 

181-182° 

lOld 

68 

103. 

2-( 2-Picolyl )phenyldichlorarsine * 





227 

104. 

2-(2-Picolyl)phenyldichlorarsine monohydrate* 





227 

105. 

2-(2-Picolyl)phenyldichlorarsine hydrochloride* 





227 

106. 

2-Dichlorarsinodibenzothiophene 

84g 

mp 

114-115° 

lOld 

68, 79 

107. 

N-Ethyl-3-dichlorarsinocarbazole 

84e 





108. 

2-Dichlorarsinodibenzo-p-dioxin 

84g 

mp 

108-109° 

lOld 

68, 79 


SECRET 


PHYSIOLOGICAL SECTION 


103 


Table 9 {Continued). 


Compound 


Reference 

to 

synthesis 


Physical properties 
Property Reference 


Reference to 
toxicity 
data 


109. 2-Dichlorarsinophenoxthiin 

84g 

mp 

64-65° 

lOld 

68, 79 

110. 6-Dichlorarsino-2-phenylbenzthiazole hydrochloride 

84h 





111. 6is(2-Dichlorarsinoethyl)sulfone 

1 

mp 

79.5-80.5° 

1 

68 

112. o-Phenylene-6fs(dichlorarsine)* 





227 

1 13. m-Phenylene-6fs(dichlorarsine)* 





227 

1 14. p-Phenylene-6fs(dichlorarsine)* 

58, 311 

d 

2.15 

311 

68, 79, 311 



mp 

97-98° 

58 




bp2o 

200° 

311 


115. 1 ,4-6fs(Dichlorarsino)-2-nitrobenzene 

58 

mp 

72.6-74.3° 

58 

68, 79 

1 16. p-Dichlorostibinophenyldichlorarsine* 





227 

1 17. 2-Dichlorarsinodiphenylchlorarsine* 





227 

118. 6fs(p-Dichlorarsinophenyl) disulfide* 

3071 

mp 

125.5-126.5° 

3071 

283, 291g 

119. 3,3 '~his{ Dichlorarsino )azoxy benzene 

58 

mp 

119-120° 

58 

68 

120. 4,4 Dichlorarsino )biphenyl* 





227 

Derivatives of secondary arsines 

121. Dimethylfiuorarsine* 





227 

122. Dimethylchlorarsine (cacodyl chloride) 

8, 38, 140, 


1.5 

38 

27, 131 


131 


1.489 

145 




bp 

103-105 

38 




voF 

254.5 

131 


1 23 . Dimethylcyanoarsine ( cacodyl cyanide ) 

58, 317 

^d39.6 

1.4859 

58 

68, 79, 151 



mp 

35.3-35.8° 

58 




bp 

160-161° 

58 


124. Dimethylthiocyanoarsine 

73 


1.6100 

73 

68, 79 




1.4695 

73 




bp2® 

106-107° 

73 


1 25 . his{ Chloromethyl )chloroarsine 

47 

d 

ca. 1.85 

27 

27, 68, 79 



bp^° 

75° 

47 


126. Reaction product of mercury chloroacetylide and ar- 
senic trichloride* 





227 

127. 6fs(2-Chlorovinyl)chlorarsine* (lewisite II) 

311 

riD^ 

1.6096 

311 

235, 311 



dll 

1.7047 

311 




bpii 

112° 

311 




bp®“ 

136° 

311 


1 28 . his{ 2-Chloro vinyl )cyanoarsine * 





227 

129. 6fs( 2,2-Dichloro vinyl )chloroarsine* 

311 




311 

1 30. his{ 2-Bromo vinyl )bromoarsine * 

231 

bpi® 

153-158° 

231 

231 

131 . 6fs( 1,2,2-Trichloro vinyl )chloroarsine* 

231 

bp® 

141° 

231 

231 

132. Diethylchlorarsine 

58 


1.5080 

58 

68, 79 



cPs 

1.368 

58 




bpi® 

52-54° 

58 




bp736 

156° 

58 


133. Diethylcyanoarsine 

58 

np” 

1.4863 

58 

68, 79 



d2® 

1.238 

58 




bpi® 

80-81° 

58 




bp^®7 

190-191° 

58 


134. Ethylpropylchlorarsine 

39 

d®» 

1.330 

39 

68, 79 



bp®i 

82-85° 

39 




bp729 

176° 

39 


135. Ethylpropylcyanoarsine 

58 


1.4838 

58 

68, 79 



d^ 

1.194 

58 




bp27 

110-113° 

58 




VOpO 

1.45 

70 

. . . 

136. Ethylpropylthiocyanoarsine 

73 


1.5674 

73 

68, 79 



d®® 

1.286 

73 




bpO.6® 

102-110° 

73 


137. Ethylbutylchlorarsine 

58 

np2® 

1.5025 

58 

68, 79 



d®® 

1.272 

58 




bpi® 

89-92° 

58 



SECRET 


104 


ARSENICALS 


Table 9 {Continued). 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Reference to 
toxicity 
data 

138. 

Ethylbutylcyanoarsine 

58 

riD^^ 

1.4828 

58 

68, 79 





1.152 

58 





bpi9 

112-112.5° 

58 


139. 

his{ 2-Chloro-3-( 2- chloroethylthio )-l-butenyl ) chlor- 







arsine* 





227 

140. 

Dibutvliodoarsine 

"84b 




68, 79 

141. 

6is(Cyclohexyl)chlorarsine* 





227 

142. 

Me t hy Iphenylarsine 

73 

d23 

1.31 

73 





bp3^ 

108-111° 

73 





bp^^ 

128-129° 

73 


143. 

Methylphenylchlorarsine 

58 


1.6022 

58 

68, 79 





1.449 

58 





bp2* 

127° 

58 


144. 

Methylphenyliodoarsine* 






145. 

Methylphenylcyanoarsine 

58 


1.5812 

58 

68, 79 





1.372 

58 





bp2“ 

147-148° 

58 


146. 

Met hylphenylthiocyanoarsine 

58 


1.6577 

58 

68, 79 




#2 

1.433 

58 





bpl5-18 

176-179° 

58 


147. 

w-Chlorophenylmeth 3 dchlorarsine* 





227 

148. 

Methyl-m-nitrophenylchlorarsine 

73 

nD®” 

1.6272 

73 

68, 79 





1.617 

73 





bpO.8 

162° 

73 


149. 

Methyl-w-nitrophenylbromoarsine 

73 


1.6551 

73 

79 




d32 

1.857 

73 





bpO.86 

174° 

73 


150. 

Methyl-m-nitrophenylcyanoarsine 

73 

mp 

79.5-80.5° 

73 

68, 79 

151. 

Methyl-2-phenoxyphenylchlorarsine* 





227 

152. 

2-Chlorovinylphenylchlorarsine 

1, 231 


1.401 

27 

68, 79, 231 




bp8 

138-145° 

231 





bp^ 

165° 

27 


153. 

w-Chlorophenyl-2-chlorovinylchlorarsine* 





227 

154. 

m-Chlorophenyl-2-chlorovinylcyanoarsine* 





227 

155. 

o-Carboxyphenylmethylchlorarsine* 





227 

156. 

«-(Phenylchlorarsino) acetic acid* 





227 

157. 

Allylphenylchlorarsine 

1 

d 

1.479 

1 

27, 68, 79 




bp® 

99.5-100° 

1 


158. 

Methylphenethylchlorarsine* 





227 

159. 

2-Chlorovinyl-a-furylchlorarsine 

267 

bp^ 

90-103° 

267 

267 

160. 

2-Chlorovinyl-a-fiirylcyanoarsine 

267 

bp® 

127-128° 

267 

267 

161. 

Ethyleiie-6is(phenylchlorarsine)* 





227 

162. 

Diphenylfliioroarsine* 





227 

163. 

Diphenylchlorarsine (DA)* 

73, 311 


1.6429 

73 

79, 68, 311, 







249 





1.413 

73 





mp 

38° 

244 





bp®-^ 

157-160° 

73 





vopo 

<0.0001 

311 


164. 

2-Chlorophenylphenylchlorarsine* 

301e 

mp 

30-35° 

301e 

227 

165. 

3-Chlorophenylphenylchlorarsine* 





227 

166. 

4-Chlorophenylphenylchlorarsine* 





227 

167. 

2-Nitrophenylphenylchlorarsine* 





227 

168. 

3-Nitrophenylphenylchlorarsine* 





227 

169. 

4-Nitrophenylphenylchlorarsine* 





227 

170. 

his{ 2-Chlorophenyl )chlorarsine 

301e 

mp 

73-75° 

301e 

227 

171. 

6is(4-Chlorophenyl)chlorarsine* 





227 

172. 

6zs(3-Nitrophenyl)chlorarsine* 

58 

mp 

112-113° 

58 

68, 79 

173. 

2-Phenylchlorarsinoaniline hydrochloride* 





227 

174. 

3-Phenylchlorarsinoaniline hydrochloride* 





227 

175. 

4-PhenylchlorarsinoaniIine hydrochloride* 





227 

176. 

5w(w-Aminophenyl)chlorarsine dihydrochloride* 





227 


SECRET 


PHYSIOLOGICAL SECTION 


105 


Table 9 {Continued). 

Compound 

Reference 

to 

synthesis 


Physical properties 

Property Reference 

Reference to 
toxicity 
data 

177. 6ts(p-Aminophenyl)chlorarsine dihydrochloride* 





227 

178. 6is(p-Methoxyphenyl)chlorarsine* 





227 

179. Diphenylbromoarsine* 

341 




121 

180. Diphenylcyanoarsine (DC)* 

311 


1.6254 

244 

311 




1.3327 

244 




mp 

31.2° 

244 




voP" 

0.0001-0.00015 

311 


181 . 2-Chlorophenylphenylcyanoarsine* 

301e 

mp 

40-42° 

301e 

227 

1 82 . 3-Chloropheny Iphenylcy anoarsine * 





227 

1 83. 4-Chlorophenylphenylcyanoarsine* 

301e 

mp 

102° 

301e 

227 

1 84 . 2-N itrophenylphenylcy anoarsine * 





227 

185. 3-Nitrophenylphenylcyanoarsine* 





227 

186. 4-Nitrophenylphenylcyanoarsine* 





227 

187. 6is(2-Chlorophenyl)cyanoarsine* 

301e 

mp 

85-87° 

301e 

227 

1 88. his{ 4-Chlorophenyl )cyanoarsine* 





227 

1 89 . his{ 3- N it rophenyl )cy anoarsine * 

58 

mp 

151-152° 

58 

68, 79 

190. 2-Phenylcyanoarsinoaniline* 





227 

191. 3-Phenyl cyanoarsinoaniline* 





227 

192. 4-Phenylcyanoarsinoaniline* 





227 

1 93 . his{ m- Aminophenyl )cy anoarsine * 





227 

194. Diphenylthiocyanoarsine* 

58, 301j 


1.6766 

58 

68, 79 




1.379 

58 




bp'*-^ 

217-219° 

58 


1 95. his{m-K itrophenyl)thiocy anoarsine 

58 

mp 

103-105° 

58 

68, 79 

196. Phenyl-o-tolylcy anoarsine* 

301e 




227 

1 97. o-Chlorophenyl-o-tolylcyanoarsine* 





227 

198. p-Chlorophenyl-o-tolylcyanoarsine* 





227 

199. o-N itrophenyl-o-t olylcy anoarsine * 





227 

200. w-N itrophenyl-o-tolylcy anoarsine * 





227 

201 . p-Nitrophenyl-o-tolylcyanoarsine* 





227 

202. Phenyl-m-tolylcyanoarsine* 





227 

203. Phenyl-p-tolylchlorarsine* 

301e 




227 

204. Phenyl-p-tolylcyanoarsine* 

301e 




227 

205. o-Chlorophenyl-p-tolylcyanoarsine* 





227 

206. m-Chlorophenyl-p-t olylcyanoarsine * 





227 

207. p-Chlorophenyl-p-tolylcy anoarsine * 





227 

208. p-Nitrophenyl-p-tolylcyanoarsine* 





227 

209 . m-( Pheny Icy anoarsino )benzaldehy de * 





227 

210. o-(Phenylchlorarsino)benzoic acid* 





227 

211. Methyl o-(phenylchlorarsino)benzoate* 





227 

212. m-(Phenylchlorarsino)benzoic acid* 

301b, 301j 

mp 

134-136° 

30ib 

301h 

213. Methyl m-(phenylchlorarsino)benzoate* 

301b, 301j 




301h 

214. Methyl m-(phenylcyanoarsino)benzoate* 

301b, 301j 




301 h 

215. p-(Phenylchlorarsino)benzoic acid* 

301b, 301j 

mp 

115-117° 

301b 

301 h 

216. Methyl p-(phenylchlorarsino)benzoate* 

301b, 301j 




301h 

217. Methyl p-(phenylcyanoarsino)benzoate* 

301b, 301 j 




301h 

218. 2,4-Dimethylphenylphenylcyanoarsine* 





227 

219. 6is(o-Tolyl)cyanoarsine* 

301e 

mp 

74° 

301e 

227 

220. 5is(o-Carbomethoxyphenyl)chlorarsine* 





227 

22 1 . o-Tolyl-m-tolylcy anoarsine* 





227 

222. o-Tolyl-p-toly Icy anoarsine* 





227 

223. 6is(m-Tolyl)cy anoarsine* 





227 

224. m-Tolyl-p-tolylcyanoarsine* 





227 

225. 6is(p-Tolyl)cy anoarsine 

301e 

mp 

62° 

301e 

227 

226. m-{ Phenylchlorarsino )acetophenone* 

301j 

mp 

71-72° 

301j 

227 

227. m-{ Phenylcy anoarsino )acetophenone* 

301j 

mp 

57-59° 

301j 

227 

228. m-(Phenylchlorarsino)-w-chloroacetophenone* 

301j 




227 

229 . m~{ Pheny Icyanoarsino )-aj-chloroacetophenone * 

301j 




227 

230. 2,4-Dimethylphenyl-o-tolylcyanoarsine* 





301f 

231. 2 ,4-Dimethylphenyl-p-tolylcyanoarsine* 





301f 

232 . a-N aphthylphenylchlorarsine * 





227 

233. /3-Naphthylphenylchlorarsine* 





227 


SECRET 


106 


ARSENICALS 


Table 9 {Continued). 


Compound 

Reference 

to 

synthesis 


Physical properties Reference to 

toxicity 

Property Reference data 

234 . a-N aphthylphenylcy anoarsine * 

301e 

mp 

98-99° 

301e 

227 

235 . j8-N aphthylphenylcy anoarsi ne* 





227 

236 . a-N aphthyl-p-tolylcy anoarsine * 





227 

237. /3-Naphthyl-p-tolylcyanoarsine* 





227 

238 . 6is(a-N aphthyl )chlorarsine 

301j 

mp 

163-165° 

301j 


239 . 6is-a-N aphthylcyanoarsine * 

301j 

mp 

191° 

301g 

301g 

240 . 6fs-/3-N aphthylchlorarsine * 





227 

24 1 . his-^-N aphthylcyanoarsine * 





227 

242 . Phenyl-( a:)-thienylchlorarsine * 

301e 

bp°-^ 

150-156° 

301e 

227 

243 . Phenyl-( x )-thienylcy anoarsine * 

301e 

mp 

49-51° 

301e 

227 



bpO.6 

168-174° 

301e 


244. Phenyl-3-pyridylchlorarsine hydrochloride* 





227 

245. Phenyl-3-pyridylchlorarsine methiodide* 





227 

246. Phenyl-3-pyridylcyanoarsine hydrochloride* 





227 

247. 5-Phenylchlorarsino)-2-chloropyridine hydrochloride* 





227 

248. 5-(Phenylchlorarsino)-2-aminopyridine dihydrochlo- 
ride* 





227 

249. 5ts(a-Furyl)chlorarsine* 

1, 25, 301d 

nv?^ 

1.6082 

25 

68, 79 




1.5909 

25 




bp^ 

122-127° 

25 


250. 6zs(a-Furyl)cyanoarsine* 

39, 301e 


1.5749 

39 

68, 79 




1.4857 

39 




bp2'‘ 

142° 

39 


251. 6ts(«-Thienyl)chlorarsine* 





227 

252. 6is(a-Thienyl)cyanoarsine* 

301e 

mp 

51-55° 

301e 

227 



bpO.61 

5 180-182° 

301e 


253. 6zs(3-Pyridyl)chlorarsine dihydrochloride* 

58 

mp 

270-273° 

58 

68 

254. 6zs(3-Pyridyl)cyanoarsine* 





227 

255. p-Phenylenechlorarsine 

1 

mp 

ca. 145° 

1 


256. 1-Chlorarsindole* 





227 

257. 2-(Diethylaminomethyl)-l,3-dichlorarsindole hy- 
drochloride 

73 

mp 

204.2-205.2° 

73 

68 

258. 5-Chlorodibenzarsenole* 

5, 307b 

mp 

161° 

5 

68 



bp25 

230° 

5 


259. 5-Chloro-3,7-dinitrodibenzarsenole* 

260 . 5-Chloro-3-aminodi benzarsenole * 





227 





227 

261. 5-Chloro-3,7-diaminobenzarsenole hydrochloride* 





227 

262. 5-Cyanodibenzarsenole* 

5 

mp 

178° 

5 

68 

263. 5-Iododibenzarsenole* 





227 

264 . 4,4 '-Dipheny lenechlorarsine * 





227 

265. 5-Chloro-5, 10-dihydroacridarsine* 

39, 307b 

mp 

113-114° 

39 

227 

266. 2, 5-Dichloro-5, 10-dihydroacridarsine* 

307m 

mp 

116° 

29 le, 307m 

291e 

267 . 5- Cyano-5, 1 0-dihy droacridarsine* 

307k 

mp 

114-115° 

307k 

285, 291d 

268. 2-Chloro-5-cyano-5, 10-dihydroacridarsine* 

307m 

mp 

113-114° 

307m 

285, 291e 

269. 5-Chloro-10-oxo-5, 10-dihydroacridarsine* 





227 

270. 5-Chloro-2-methyl-5, 10-dihydroacridarsine* 

307j 

mp 

87° 

307j 

285 

271 . 5-Cyano-2- methyl-5, 10-dihydroacridarsine 


mp 

87° 

291f 

285, 291f 

272. 5-Chloro-3-methyl-5, 10-dihydroacridarsine* 


mp 

65.5-66.5° 

307n 

291c 

273. 10- Acetyl-5, 10-dihydrophenarsazine* 





227 

274. 10- Acety]-5, 10-dihydrophenarsazine picrate* 





227 

275. lO-Trichloroacetyl-5, 10-dihydrophenarsazine* 





227 

276. 10-Chloro-5,10-dihydrophenarsazine (DM)* 

38, 73, 311 


1.648 

311 

68, 79,311, 



mp 

189-190.4° 

73 

104 



VOl"“ 

0.00002 

31 


277. 5-Acetyl-10-chloro-5, 10-dihydrophenarsazine* 





227 

278. 5-Propionyl-10-chloro-5, 10-dihydrophenarsazine* 





227 

279. 5-Benzoyl-10-chloro-5, 10-dihydrophenarsazine* 





227 

280. lO-Bromo-5, 10-dihydrophenarsazine* 





227 

281. lO-Iodo-5, 10-dihydrophenarsazine* 





227 

282. lO-Cyano-5, 10-dihydrophenarsazine (Cyan DM)* 

107, 108 




121 

283. lO-Thiocyano-5, 10-dihydrophenarsazine* 





227 


SECRET 


PHYSIOLOGICAL SECTION 


107 


Table 9 {Continued). 


Compound 


Reference 

to 

synthesis 


Physical properties 
Property 


Reference to 
toxicity 
Reference data 


284. 

1 (or 3), lO-Dichloro-5, 10-dihydrophenarsazine* 




227 

285. 

2, lO-Dichloro-5 ,1 0-dihy drophenarsazine * 




227 

286. 

10-Chloro-5,10-dihydro-4 (?)-nitrophenarsazine* 




227 

287. 

1 (or 3 ) ,2, 1 0-Trichloro-5, 1 0-dihydrophenarsazine* 




227 

288. 

1, 3, lO-Trichloro-5, 10-dihydrophenarsazine* 




227 

289. 

l,9(or 3,7), lO-Trichloro-5, 10-dihydrophenarsazine* 




227 

290. 

2 , 8, 1 0-Trichloro-5, 1 0-dihy drophenarsazine * 




227 

291. 

1 ,2 , 3, 1 0-Tetrachloro-5 , 1 0-dihy drophenarsazine * 




227 

292. 

2,4,6,8,10-Pentabromo-5, 10-dihydrophenarsazine* 




227 

293. 

2- Amino- 1 0-chloro-5 , 1 0-di hy drophenarsazine hydro- 






chloride* 




227 

294. 

l(or 3)-Amino-10-chlorO' 5, 10-dihydrophenarsazine 






hydrochloride* 




227 

295. 

4-Amino-10-chloro-5, 10-dihydrophenarsazine hydro- 






chloride* 




227 

296. 

1 0-Chloro-5, 10-dihydro-l ( or 3 )-methylphenarsazine * 




227 

297. 

1 0-Chloro-5 , 1 0-dihy dro-2-me thylphenarsazine * 




227 

298. 

5- Acetyl- 1 0-chloro-5 , 1 0-dihy dro-2-methylphenarsa- 






zine* 




227 

299. 

1 0-Chloro-5 , 1 0-dihy dro-4- me thylphenarsazine * 




227 

300. 

1 ( or 3 ) , 1 0-Dichloro-5 , 1 0-dihy dro-6-methylphenar- 






sazine* 




227 

301. 

4- Amino- 1 0-chloro-5 , 1 0-dihy dro-7-methylphenar- 






sazine hydrochloride* 




227 

302. 

10-Chloro-5,10-dihydrophenarsazine-l(or 3) carboxy- 






lie acid* 




227 

303. 

lO-Chloro-5, lO-dihydrophenarsazine-4-carboxylic acid* . . . 
lO-Chloro-5, 10-dihydro-l (or 3)-6-dimethylphenar- 




227 

304. 






sazine* 




227 

305. 

10-Chloro-5,10-dihydro-2,8-dimethylphenarsazine* 




227 

306. 

5- Acetyl- lO-chloro-5, 10-dihydro-2,^dimethylphenar- 






sazine* 




227 

307. 

1 (or 3)- Acetyl- 10-chlor 0-5, 10-dihydrophenarsazine* 




227 

308. 

1 ( or 3 )- Ace to-lO-bromo-5 , 10-dihydrophenarsazine* 




227 

309. 

1 0-Chloro-5 , 1 0-dihy dro- 1 ,4, 7-trimethylphenarsazine * 




227 

310. 

10-Chloro-5,10-dihydro-2,4,7-trimethylphenarsazine* 




227 

311. 

1 0-Chloro- 5 , 10-di hydro- 1 ( or 3 )-propionylphenar- 






sazine* 




227 

312. 

12-Chloro-7,12-dihydrobenz (a) phenarsazine* 




227 

313. 

7-Chloro-7,12-dihydrobenz (c) phenarsazine* 





314. 

12-Chloro-7,12-dihydroquino (5,6,b) benzarsazine* 




227 

315. 

12-Chloro-7,12-dihydro-10-methylbenz (a) phenar- 






sazine* 




227 

316. 

7-Chloro-7,12-dihydro-9-methylbenz (c) phenarsa- 






zine* 




227 

317. 

14-Chloro-7,14-dihydrodibenz-(a,j) phenarsazine* 




227 

318. 

7-Chloro-7,14-dihydrodibenz-(c,h) phenarsazine* 




227 

319. 

5,13-Dichloro-5,8,13,14-tetrahydro (1,4) benzarsa- 






zino (2,3,a) phenarsazine* 




227 

320. 

12,14-Dichloro-5,7,12,14-tetrahydro (1,4) benzarsa- 






zino (3,2,b) phenarsazine* 




227 

321. 

2,2 '-6is( 10- chloro-5, 10-dihydrophenarsaz i ne ) * 




227 

322. 

10-Chlorophenoxarsine* 288a, 307b 

mp 

120° 

307b 

227 

323. 

4,10-Dichlorophenbxarsine* 




227 

324. 

10-Cyanophenoxarsine* 




227 

325. 

12-Chloro-5,12-dihydrobenz (i) phenoxarsine* 




227 

326. 

1 0-Chlorophenthiarsine * 




227 

327. 

5,10-Dichloro-5,10-dihydroarsanthrene* 4, 110 

mp 

185-186° 

4 

121 

328. 

2,5, lO-Trichloro-5, 10-dihydroarsanthrene* 




227 

329. 

2-Amino-5,10-dichloro-5,10-dihydroarsanthrene hy- 






drochloride* 




227 

330. 

5,10-Dicyano 5,10'dihydroarsanthrene* 




227 

331. 

5, lO-Dichloro-5, lO-dihydro-5-arsa-lO-stibanthrene* 




227 


SECRET 


108 


ARSENICALS 


Table 9 {Continued). 



Compound 

Reference 

to 

synthesis 


Physical properties 

Property Reference 

Reference to 
toxicity 
data 

Tertiary arsines 






332. 

6ts(Chloromethyl)methyl arsine* 





227 

333. 

2-Chloroethyldimethylarsine* 

307p 

bp 

100-103° 

307p 

227 

334. 

5is(2-Chloro vinyl )methylarsine 

58 


1.5665 

58 

68, 79 





1.473 

58 





bpi» 

97-103° 

58 





voP” 

1.72 

70 


335. 

his{ 2-Chloroethyl )met hy larsine * 

307p 

bp®® 

50-55° 

307p 

227 

336. 

2-Iodoet hyl )methy larsine 

307p 

bp^® 

68-69° 

307p 


337. 

6?s(2-Ethoxyethyl)methylarsine 

58 


1.4664 

58 

68, 79 





1.100 

58 





bp2® 

124-125° 

58 





bp^24 

230° 

58 


338. 

fm(2-Chloro vinyl )arsine* 

73 




227 

339. 

<m(2,2-Dichlorovinyl)arsine* 





227 

340. 

Triethylarsine 

102 




68, 79 

341. 

2- Chloroethyldiethylarsine* 

307p 

cr 

53° 

307p 

227 

342. 

2-Bromoethyldiethy larsine* 





227 

343. 

6is( 2-Chloroethyl )et hy larsine * 

307p 

bp*2 

64° 

307p 

227 

344. 

tris{ Cyclohexyl )arsine 

39 

bp2 

187-189° 

39 

68, 79 

345. 

Trioctvlarsine 

101a 


0.9357 

101a 

68, 79 




bp*® 

238-240° 

101a 





bp* 

184-185° 

101a 


346. 

Phenylarsenophosgene 

84i 





347. 

2-( p-Dimethylarsinophenyl )quinoline 

84j 





348. 

6zs(2-Chloro vinyl )phenylarsine* 

1, 231 


1.384 

1 

68, 231 




bp*® 

166-171° 

231 


349. 

2-Chlorovinyldiphenylarsino* 

1 


1.327 

1 

68 

350. 

Triphenylai'sine 

73 

mp 

58-60.5° 

73 


351. 

iris{ m-N itrophenyl )arsine 

7 





352. 

/ns(p-Dimethylaminophenyl)arsine sulfur monochlo- 







ride addition product* 





227 

353. 

Tri-p-tolylarsine* 





227 

354. 

Dimethyl-2-pyridylarsine 

84j 




68, 79 

355. 

Difurylmethylarsine* 

301e 




267 

356. 

2-Chlorovinyl-?)fs(2-furyl)arsine 

267 

bp® 

127° 

267 

267 

357. 

fr? s( 2-Fury 1 )arsine * 

25, 301d 


1.436 

25 

27 




mp 

33.5° 

25 





bp® 

153° 

25 





bp4® 

162.5° 

25 


358. 

<m( 5-ier/-Butyl-2-f uryl )arsine 

101b 

mp 

53° 

101b 

68, 79 




bp* 

168° 

101b 


359. 

fm( 2-Thienyl )arsine* 

39, 301e 

riD-' 

1.6943 

39 

68, 79 





1.509 

39 





bp2 ® 

227-230° 

39 


360. 

im(2-Pyridyl )arsine 

84c 

mp 

79-81° 

101c 

68, 79 

361. 

<m(4-Dibenzofuryl)arsine 

84h 





362. 

<m(4-Dibenzothienyl)arsine 

84g 

mp 

328-329° 

lOld 


363. 

tris{ N -?]thyl-2-carbazolyl )arsine 

84d 





364. 

fm( N-Ethyl-3-carbazolyl )arsine 

84h 





365. 

<m(4-Phenoxthienyl )arsine 

84g 




68, 79 

366. 

5,10-Dihydro-10-methylphenarsazine* 





227 

367. 

5,10-Dihydro-10-ethylphenarsazine* 





227 

368. 

5, 10-Dihydro- 10-phenylphenarsazine* 





227 

369. 

6is(Dimethylarsino)acetylene 

73 

nn®-* 

1 .5662 

73 

68, 79 




d®® 

1.458 

73 





bp®® 

96-98° 

73 





bp*4 

84.5° 

73 


370. 

p- Phenylene-6fs( di methy larsine ) 

84k 




68, 79 

Quaternary arsenic derivatives 






371. 

o-Dimethylarsinophenyl-N-methylcarbamate 







methiodide 

84t 

mp 

130-132° 

84t 



SECRET 


PHYSIOLOGICAL SECTION 


109 


Table 9 {Continued). 




Compound 

Reference 

to 

synthesis 

Physical properties 
Property Reference 

Reference to 
toxicity 
data 

372. m-Dimethylarsinophenyl-N-methylcarbamate 

methiodide 

84u 

mp 

187-189° 

84u 


373. p-Dimethylarsinophenyl-N.N-dimethylcarbamate 
methiodide 

84t 

mp 

226.5° 

84t 


374. m-Diethylarsinophenol methiodide 

84v 

mp 

87-89° 

84v 

80 

375. wi-Diethylarsinophenyl-N-methylcarbamate methio- 
dide 

84v 





376. 5,10-Dihydro-10-methylphenarsazine methiodide* 





227 

377. Tetraphenylarsoniiim chloride monohydrate 

73 

mp 

262-263.5° ^ 

73 


Arsenic analogs of hydrazine 

378. 6is(Dimethylarsine) (cacodyl) 

316 





379. 5is(Diethylarsine) (ethyl cacodyl) 

17 





380. his{ Phenyl-3-pyridylarsine )* 





227 

381. his{ 2- Amino- 3-py ridylphenylarsine ) * 





227 

382. 10, 10'-6^s(5, 10-Dihydrophenarsazine)* 





227 

383 . 1 0, 1 0 6is( 5- Acetyl-5 , 1 0-dihy drophenarsaz ine ) * 





227 

384. 10,10'-6is(5,10-Dihydrophenarsazine) sulfate* 





227 

385. 2,2',4,4',6,6'-Hexanitroarsenobenzene 

7 





386. 4,4'-Dihydroxy-3,3'-dinitroarsenobenzene 

7 





387. 4,4 '-Dihydroxy-3,3 ',5,5 '-tetranitroarsenobenzene 

7 





Derivatives of arsenic oxides, sidfides, and amines 

388. Arsenic oxide* 





227 

389. Ethoxydichlorarsine 

841 




68, 79 

390. Dimethylaminodifluoroarsine 





68 

391. Isopropoxydichlorarsine 

84m 

bp737 

155-156° 

84m 


392. 2-Chloro-4,5-dihydro-l ,3,2-oxthiarsenole 

84m 

nrt^* 

1.6690 

84m 

68, 79 




1.988 

84m 




bpO.3 

72-73° 

84m 


393. Diethoxychlorarsine 

841 




68, 79 

394 . his{ 2-Chloroethoxy )chlorarsine 

47 

bp^-2 

112-118° 

47 

68 

395. Diisopropoxyfluorarsine 

84j 





396 tris{ 2-Fluoroet hoxy )arsine 

86 




68 

397. tris{ 2-Chloroe thoxy )arsi ne 

47 

bp^” 

160-170° 

47 

68 

398. <rfs(2-Chloroethylthio)arsine* 

84r 


1.5972 

84r 

68 

399. tn‘s(Phenylthio)arsine 

84o 

mp 

92-94° 

84o 

68 

400. Methylarsine disulfide* 





227 

401. Phenylmethoxychlorarsine* 





227 

402. Phenylethoxychlorarsine* 





227 

403. Phenyl-2-chloroethylthiochlorarsine* 

297a 




227 

404. o-Hydroxychlorarsinobenzoic anhydride* 

58 

mp 

146.5-147° 

58 

68 



bp^' 

233-236° 

58 


405. o-Phenylenediarsine oxychloride* 

73 

mp 

150.5-151.5° 

73 

68 

406. Methylarsenic oxide* 

311 

mp 

95° 

311 

311 



bp 

ca. 275° 

311 


407. Methylarsenic sulfide* 





227 

408. Methyldimethoxyarsine* 





227 

409. Methyldimethylthioarsine* 





227 

410. Methyldiethoxyarsine* 





227 

411. Methyl-6fs(N,N-diethyldithiocarbamyl) arsine* 





227 

412. Methyl-5fs( N , N -bis{ 2-hy droxyethyl )dit hiocar- 
bamyl)arsine* 





227 

413. Methyldiphenylthioarsine* 





227 

414. Methyldi-p-tolylthioarsine* 





227 

415. 2-Chlorovinylarsenic oxide (various isomers)* 

416. 2-Chlorovinylarsenic sulfide* 

12, 311 

Physical properties vary 
with method of prepa- 
ration 

122, 12 

68, 79 

227 

417. 2-Chlorovinylarsenic selenide 

67 




68 

418. 2-Chlorovinyldimethoxy arsine 





68, 79 


SECRET 


110 


ARSENICALS 


Table 9 {Continued). 


Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Reference to 
toxicity 
data 

41 9. 2-Chlorovinyldimethylthioarsine 





68, 79 

420. 2-Chlorovinyldiethoxy arsine* 

30 

bpi7-i8 

84-85® 

30 

68, 79 

421 . 2-Chlorovinyl-6is(2-chloi’oethylthio)arsine* 

84p 


1.6400 

84p 

68, 79 




1.610 

84p 




bp^ 

84-86° 

84p 


422 . 2-Chlorovinyl-6is( 2-ethoxyethoxy )arsine * 





227 

423. 2-Chlorovinyl-6zs(2-hydroxyethylthio)arsine 

33 

bp2.5-3 

85.1-86.7° 

33 

68 

424 . 2-Chlorovinyldiallyloxy arsine * 





227 

425 . 2-Chlorovinyldiisopropoxy arsine * 





227 

426 . 2-Chlorovinyldipentoxy arsine * 





227 

427. 2-(2-Chlorovinyl)-5,5-6is(hydroxymethyl)-4, 5-dihy- 
dro- 1 , 3, 2-dithiarsin 

33 

mp 

127.5-128.5° 

33 

68 

428. 2-Chlorovinyldiisoocty loxy arsi ne * 





227 

429. 2-Chlorovinyldiphenylthioarsine* 





227 

430. 2-Chlorovinyl-6^s(N,N-diethyldithiocarbamyl)ar- 
sine* 





227 

431. Ethylarsenic oxide* 

103a, 311 

Wd”® 

1.5821 

311 

68, 79 



^11.5 

1.8019 

311 




bp^ 

119° 

103a 


432. Ethyldimethylthioarsine 





68 

433. Ethyh his{ 2-chloroethoxy )arsine 

103b 




68 

434. Ethyldipropoxy arsine 

58 

^j^30.5 

1.4466 

58 

68, 79 



d” 

1.114 

58 




bp^^ 

86-90° 

58 




bp738 

185-186° 

58 


435. N-Ethylethylarsenimide 

58 


1.5681 

58 

68, 79 




1.498 

58 



... # 

bp3.5 

165-175° 

58 


436. Propyldiacetoxy arsine 

58 


1.4715 

58 

68, 79 




1.335 

58 




bp^^ 

120-123° 

58 


437. Amylarsenic oxide 

35 




438. Isoamylarsenic oxide 

35 





439. Hexylarsenic oxide 

35 





440. Phenylarsenic oxide* 

39, 311 

mp 

118-120° 

39 

68, 291a 

441. o-Nitrophenylarsenic oxide 

7 

(But varies with method 
of preparation) 

311 


442. m-Nitrophenylarsenic oxide 

58 

mp 

184.5-187.5° 

58 

68, 79 

443. 2,4,6-Trinitrophenylarsenic oxide 

7 





444. 2,4,6-Trinitrophenylarsenicdinitrate 

7 





445. Phenyl-6is(2-chloroethylthio)arsine* 

297a 




227 

446. p-Hydroxyphenylarsenic oxide* 





227 

447. w-Aminophenylarsenic oxide* 





227 

448. p-Dimethylaminophenylarsenic oxide* 

7 




291b 

449. 3-Amino-4-hydroxyphenylarsenic oxide hydrochlo- 
ride (Mapharsen) 

Commercial 




334 

450. o-Arsenosobenzoic acid* 





227 

451. m-Arsenosobenzoic acid* 





227 

452. 3-Pyridylarsenic oxide* 





227 

453. 2-Chloropyridine-5-arsenic oxide* 





227 

454. 2-Dibenzothienylarsenic oxide 

84f 





455. 4,4'-6ts(Arsenoso)biphenyl* 





227 

456. 6is(Dimethylarsenic) oxide (cacodyl oxide) 

8, 38 

bp 

149-151° 

38 

68, 79 

457. 2-Chloroethylthiodimethylarsine 

84m 

bpi^ 

94-95° 

84m 

68, 79 

458. 6is(Dimethylarsenic) disulfide* 





227 

459. 6is(Diethylarsenic) oxide 

17 





460. 5ts(6is-2-Chlorovinylarsenic) oxide 





235 

461 . 6is(2-Chlorovinyl)-2-chloroethylthioarsine 

84q 


1.6085 

84q 

68 



bpO-5 

128-129° 

84q 


462. 5is(2-Chlorovinyl)-l ,3-dichloropropyl-2-thioarsine 

84s 

bp“-2 

148-151° 

84s 

68 


SECRET 


PHYSIOLOGICAL SECTION 


111 


Table 9 {Continued). 


Compound 

Reference 

to 

synthesis 


Physical properties 
Property Reference 

Reference to 
toxicity 
data 

463. Methylphenylmethoxy arsine 

58 

n\)^^ 

1.5613 

58 

68, 79 




1.295 

58 




bp^®“ 

-17 101 - 102 ° 

58 


464. Met hylphenylacetoxy arsine 

58 


1.5612 

58 

68, 79 




1.369 

58 




bp^^ 

140-142° 

58 


465. 2-Chloroethylthiodiphenylarsine* 





227 

466. Benzoxydiphenylarsine* 





227 

467. 6rs(Diphenylarsenic) oxide* 





227 

468. 5is(Diphenylarsenic) sulfide* 

301j 

mp 

58-60° 

301 j 

227 

469. 6is(6is-(p-Aminophenyl) arsenic) oxide* 





227 

470. o-Phenylhydroxyarsinobenzoic acid anhydride* 





227 

471. 6rs(o-Carboxy phenyl) hydroxy arsine anhydride* 





227 

472. 6is(o-Carboxyphenylphenylarsenic) oxide* 





227 

473. 52s(p-Carboxyphenylphenylarsenic) oxide* 





227 

474. p-Phenylene-6is(phenylarsine) monoxide* 





227 

475. Acetoxydithienylarsine* 





227 

476. 1,3-Dihydroxyarsindole* 





227 

477. 6is(Dibenzarsenyl-5) oxide* 





227 

478. 6fs(3,7-Dinitrodibenzarsenyl-5) oxide* 





227 

479. 6zs(3-Aminodibenzarsenyl-5) oxide* 





227 

480. 5ts(Phenoxarsinyl-10) oxide* 

288a 

mp 

182° 


227 

481 . lO-Chloroethylthio-5, lO-dihydrophenarsazine 

84n 

mp 

128-153° 

84n 


482. bzs(5,10-Dihydrophenarsazinyl-10) oxide* 





227 

483. 6is(5,10-Dihydrophenarsazinyl-10) sulfide* 

484. 6is(5,10-Dihydrophenarsazinyl-10) oxide. 10-Chloro- 





227 

5,10-dihydroplienarsazine (basic DM)* 





227 

485. 5^s(5-Acetyl-5,10-dihydrophenarsazinyl-10) oxide* 





227 

486 . his{ 5-Benzoyl-5 , 1 0-dihy drophenarsazinyl- 10) oxide * 





227 

487. 5,10-Dihydroarsanthrene-5,10 monoxide* 

488. 5,10-Dihydro-5,10-dioxystibarsanthrene-5,10 mon- 





227 

oxide* 





227 

Halogen and oxygen derivatives of tertiary arsines 

489. Triphenyldichlorarsine* 





227 

490. Tri-m-nitrophenyldibromoarsine 

7 





491. Tri-p-tolyldichlorarsine* 





227 

492. Tri-m-nitrophenylarsenic oxide 

7 





493. Tri-m-nitrophenylarsenic dinitrate 

7 

mp 

147-148° 

7 


494. o-Carboxyphenylphenylmethylarsenic oxide* 

495. 7-Phenylmethyloxidoarsino-2-naphthalenesulfonic 





227 

acid* 





227 

Derivatives of arsenic, arsonic, and arsinic acids 

496 o-Nitroanilinium arsenate 

7 

mp 

146-147° 

7 


497. w-Nitroanilinium arsenate 

7 

mp 

114-115° 

then 

7 





147-148° 

7 


498. p-Nitroanilinium arsenate 

7 

mp 

77-78° 

7 


499. Sodium methanearsenate hydrate 

69 




68 

500. 2-Chloroethylenearsonic acid* 

69 

mp 

129° 

69 

68, 79 

501. Ethanearsonic acid 

69 

mp 

96° 

69 

68 

502. Benzenearsonic acid 

58 

mp 

165° 

58 

68, 79 

503. o-Nitrobenzenearsonic acid 

7 





504. Cadmium o-nitrobenzenearsonate 

34 





505. Lead o-nitrobenzenearsonate 

7 





506. m-Nitrobenzenearsonic acid 

7 





507. Lead m-nitrobenzenearsonate 

7 





508. p-Nitrobenzenearsonic acid 

7 





509. Sodium 2,4-dinitrobenzenearsonate 

510. Magnesium 2,4-dinitrobenzenearsonate 

7 





84a 





511. Potassium 2,4-dinitrobenzenearsonate 

84a 






SECRET 


112 


ARSENIC ALS 


Compound 


Table 9 {Continued). 


Reference 

to 

synthesis 


Physical properties 
Property Reference 


Reference to 
toxicity 


data 


512. Manganous 2,4-dinitrobenzenearsonate 84a 

513. Ferric 2,4-dinitrobenzenearsonate 84a 

514. Cobalt 2,4-dinitrobenzenearsonate 84a 

515. Nickel 2,4-dinitrobenzenearsonate 84a 

516. Cupric 2,4-dinitrobenzenearsonate 84a 

517. Cadmium 2,4-dinitrobenzenearsonate 34 

518. Stannic 2,4-dinitrobenzenearsonate 84a 

519. Barium 2,4-dinitrobenzenearsonate 84a 

520. Mercuric 2,4-dinitrobenzenearsonate 84a 

521. Lead 2,4-dinitrobenzenearsonate 101b 

522. 2,4,6-Trinitrobenzenearsonic acid 7 

523. Sodium 2,4,6-trinitrobenzenearsonate 84a 

524. Potassium 2,4,6-trinitrobenzenearsonate 84a 

525. Calcium 2,4,6-trinitrobenzenearsonate 84a 

526. Cupric 2,4,6-trinitrobenzenearsonate 84a 

527. Cadmium 2,4,6-trinitrobenzenearsonate 34 

528. Stannic 2,4,6-trinitrobenzenearsonate 84a 

529. Barium 2,4,6-trinitrobenzenearsonate 84a 

530. Mercuric 2,4,6-trinitrobenzenearsonate 84a 

531. Lead 2,4,6-trinitrobenzenearsonate 7 

532. p-Hydroxybenzenearsonic acid* 

533. 4-Hy droxy- 3-nit robenzenearsonic acid 7 

534. Lead 4-hydroxy-3-nitrobenzenearsonate 7 

535. 4-Hydroxy-3,5-dinitrobenzenearsonic acid 7 

536. Cadmium 4-hydroxy-3,5-dinitrobenzenearsonate 34 

537. Lead 4-hydroxy-3,5-dinitrobenzenearsonate 7 

538. Cadmium 2,4-dihydroxy-3,5-dinitrobenzenearsonate 34 

539. o-Arsanilic acid* 

540. 2-Amino-5-nitrobenzenearsonic acid* 

541. p-Arsanilic acid picrate 7 

542. 4-Amino-3,5-dinitrobenzenearsonic acid 7 

543. Lead 4-amino-3,5-dinitrobenzenearsonate 7 


544. o-Toluenearsonic acid* 

545. 2-Biphenylarsonic acid* 

546. 4,4'-Biphenyldiarsonic acid* 

547. 2-Benzophenonearsonic acid* 

548. 8-Methylquinoline-5-arsonic acid 84f 

549. 2-Dibenzothiophenearsonic acid 84f 

550. N-Ethylcarbazole-3-arsonic acid 84e 

551. 1,3-Dihydroxy-l-oxyarsindole* 

552. 5-Hydroxy-5-oxydibenzarsenole* 

553. 5,10-Dihydro-10-hydroxy-10-oxyphenarsazine* 

554. 5,10-Dihydro-10-hydroxy-10-oxyphenarsazine hy- 

drochloride* 

555. 10,10-Dihydroxy-10-ethylphenoxarsine* 

556. 5,10-Dihydro-10,10-dihydroxy-10-ethylphenarsazine* 

Arsenic derivatives of uncertain constitution 

557. Chlorination product of Propane- 1,3-diarsonic acid* 

558. By-product of the preparation of dimethylaminodi- 

fluoroarsine 

559. Anhydride from o-hydroxyphenylarsenic oxide* 

560. Di(6is(5,10-dihydrophenarsazine- 10)o.xalate)-acetate* 


mp 


mp 


169 


72 


50 


170° 


227 


227 

227 


227 

227 

227 

227 


227 

227 

227 

227 

227 

227 


227 

68 

227 

227 


No compounds of unusual toxicity were discovered 
in this class, and, although some of the members ap- 
peared to offer potentialities as irritant smokes, none 
showed evidence of being significantly better than 
the standard irritants DM, DA, and D(k 


7.3.4 Irritant Arsenical Smokes 

Certain arsenical compounds which are relatively 
nonvolatile and of fairly low toxicity are, neverthe- 
less, highly irritating to the respiratory tract when 
disj)ersed as a cloud of very fine particles. Further- 




SECRFT 


PHYSIOLOGICAL SECTION 


113 


more, such particles will penetrate gas mask can- 
isters unless the canisters are fitted with an efficient 
particulate filter. Such filters were not available in 
World War I, but have since been developed and are 
standard equipment of all nations. 

Diphenylchlorarsine (DA) was introduced by the 
Germans in 1917 as a mask-breaking irritant wffiich 
w'as expected to produce temporary casualties and to 
cause troops to unmask and expose themselves to the 
effects of more lethal agents, usually employed simul- 
taneously. In 1918 diphenylcyanoarsine (DC) was 
used for the same purpose. 

The Allies claimed that these agents w^ere not very 
effective but w'ere inclined to attribute their lack of 
success in part to the German method of dispersal of 
the agents.^^^ The Americans produced a new respira- 
tory irritant diphenylaminechlorarsine (DM), usu- 
ally called adamsite after its discoverer. Dr. Roger 
Adams. DM was not used in World War I, but was 
adopted by the United States as their standard irri- 
tant smoke and has been found to be useful in riot con- 
trol, since only temporary casualties are produced. 

During World War I, the method of dispersing the 
irritant smokes was in artillery shell employing a 
large burster charge. The particles obtained by this 
method are too large to obtain maximal effect from 
the agent. The method now used consists of volatil- 
ization of the arsenical in a cloud of hot gas produced 
in a thermal generator. The hot arsenical vapor con- 
denses to a cloud of very minute particles on contact 
with the air. 

The Japanese used irritant smoke candles on a 
number of occasions against both Chinese and Ameri- 
can troops, although the attacks were aUvays on a 
small scale and were apparently undertaken by group 
commanders without the sanction of the high com- 
mand. 

Physiological Action 

The physiological action of the irritant smokes has 
been summarized in the open literature. The effects 
of exposure consist of severe irritation to the nose 
and throat resembling that from a heavy cold. There 
is much sneezing, wintering of the eyes, and flow of 
mucous from the nose. Headache, pain in the ears 
and gums, and nausea are frequently encountered. 
A feeling of depression often accompanies exposure 
to the arsenical smokes and is thought to be largely 
psychological in origin. 

Toxicity 

The L(C05 o’s by inhalation of DA, DC, and DM 


have not been determined wflth very great accuracy 
for many species, but figures quoted lead to the 
conclusion that the L(C 0 50 for man would be greater 
than 10 mg min/1. Since the particulate clouds are 
nonpersistent, death from inhalation of the arsenical 
smokes could be expected only under very unusual 
circumstances. 

British experiments have indicated that men 
exposed to relatively high concentrations of DC 
(0.00265 mg/1) for periods of 15 to 30 seconds and re- 
exposed to the same concentration four times at half- 
hourly intervals, do not show any cumulative toxic 
effect but rather develop some tolerance to the agent. 

A number of compounds were examined by the 
British 273-275 ,29id-29ig without revealing any more 
effective than DC, DA, and DM. From the effect of 
DC on rabbit eyes it has been concluded that a drop 
of <0.4 mm in diameter wmild probably not cause 
permanent damage to the human eye, but that 
greater contamination than this might exert a gross 
caustic effect which if untreated might lead to total 
loss of the eye.^^“ 

Assessment of Military Value 

The particulate filter of modern gas masks affords 
adequate protection against the irritant smokes. 
Such agents would only be of value, therefore, if they 
could be used for surprise effect before the men could 
mask. 

Acting on the suspicion that the effects of exposure 
to the irritant smokes was largely psychological, the 
British carried out important experiments in 1942 
in wffiich a group of troops exposed to DA and a con- 
trol group exposed to a harmless smoke were put 
through an assault course test. The troops were 
strongly motivated to turn in a good performance 
and were unaware of the fact that there was any dif- 
ference in the two types of smoke. The group exposed 
to DA remained in a cloud for 2 minutes or until the 
generator had burned out, and the mean concentra- 
tion of DA was 0.0266 mg/1. The results showed that 
the performance of about two- thirds of the group 
exposed to DA was hardly affected at all, that the 
performances of the remaining one-third over the 
assault course was definitely slower than the control 
group, and that about 7 per cent of the men exposed 
to DA were unable to complete the assault course. 
In view of the proximity of the men to the DA gen- 
erator and the length of exposure, it was concluded 
that the dosage of DA was greater than could be ex- 


SECRET 


114 


ARSENICALS 


pec ted in the field. Further experiment led to the 
following conclusions: 

1. The effect on fresh troops of DA in concentra- 
tions practicable under active service conditions is 
almost negligible, apart from the fact that one man 
in ten would have great difficulty in keeping on his 
gas mask when doing heavy work. 

2. Experiments on tired troops suggest that con- 
centrations of DA practicable under active service 
conditions give an average effect which is equivalent 
to making fresh troops wear their gas masks. 

3. Hence, DA is not an effective weapon even 
when used against tired men. 

In view of these findings and the failure to dis- 


cover an arsenical smoke significantly more effective 
than DA, DC, and DM, little interest remains in the 
irritant smokes as chemical warfare agents. 

7.4 TABULATION OF ARSENICALS 
EXAMINED AS CANDIDATE 
CHEMICAL WARFARE AGENTS 

Table 9 comprises as complete as possible a tab- 
ulation of arsenical compounds that have been 
examined as candidate chemical warfare agents. Ref- 
erences to synthesis, physical properties, and tox- 
icological screening data are included. 


SECRET 


Chapter 8 

ALIPHATIC NITROSOCARBAMATES AND RELATED COMPOUNDS 

By Marshall Gates and Birdsey Renshaw 


8.1 INTRODUCTION 

A SURVEY CONDUCTED by the National Defense 
Research Committee [NDRC] revealed that 
ethyl N-methyl-N-nitrosocarbamate (‘‘nitrosometh- 
ylure thane”) was one of the most disagreeable and 
toxic commercially available compounds which had 
not received careful study in connection with chemi- 
cal warfare.^ Although it proved to be insufficiently 
toxic to compete with standard agents, synthesis 
and assay of related compounds revealed a number 
of highly toxic substances. The most promising of 
these was methyl N-(j8-chloroethyl)-N-nitrosocarba- 
mate (KB- 16). 

KB- 16 is a persistent agent with a volatility only 
slightly less than that of mustard gas (H). Its syn- 
thesis, although more involved than that of H, of 
lewisite (L), or of the nitrogen mustards, presents no 
great difficulty and the required starting materials 
are readily available. 

KB-16 came under investigation in 1942 at a time 
when the nitrogen mustards were being seriously 
considered. It was quickly shown that the compound 
possesses some of the desirable characteristics of 
methyl-6is (jS-chloroe thy 1) amine (HN2) — low freez- 
ing point, lack of pronounced odor, and effectiveness 
as an eye-injurant at low dosages. Interest was also 
aroused by the finding that for mice it is three times 
as toxic as H. 

Subsequent investigations revealed that: (1) KB-16 
possesses inadequate storage stability, and no satis- 
factory stabilizer has been found in spite of intensive 
search; (2) its eye-injuring potency is not of a differ- 
ent order from that of H or (jS-chloroe thy 1) amine 
(HNS); (3) although more toxic than H and the 
nitrogen mustards for mice, it is not so toxic as these 
substances for larger species (i.e,, dogs, goats, and 
monkeys); and (4) as a vesicant it is markedly in- 
ferior to H. Taking these and other findings into ac- 
count, assessment of the merits and limitations of 
KB-16 led to the conclusion that it does not possess 
the general utility of the standard agent, H, or of the 
potentially available nitrogen mustard, HNS. Ac- 

“ Ba.sed on information available to NDRC Division 9 as of 
November 1, 1945. 


cordingly, KB-16 is not now seriously considered for 
use in chemical warfare. 

8.2 SYNTHESIS AND PROPERTIES 

8.2.1 Synthesis 

The aliphatic nitrosocarbamates tested during 
World War II (see Table 1) were prepared by nitro- 
sation of the corresponding carbamates, which in 
turn were derived from the action of alkyl chloro- 
formates on amines. The synthesis of methyl N-(j3- 
chloroethyl)-N-nitrosocarbamate (KB-16), the only 
member of the series that has received detailed study, 
involves the following steps. 

1. Preparation of N- (j3-chloroe thy 1) carbamate. 
Thionyl chloride is allowed to react with ethanol- 
amine hydrochloride to produce jS-chloroethylamine 
hydrochloride, which is then treated with methyl 
chloroformate. Alternatively, methyl chloroformate 
can be treated with ethanolamine and the resulting 
methyl N-(jS-hydroxyethyl) carbamate converted to 
the desired product by the use of thionyl chloride. 
The first of these alternatives is preferable (see be- 
low). Attempts to prepare methyl N-(/3-chloroethyl)- 
carbamate directly by the action of methyl chloro- 
formate on ethyleneimine have not succeeded.^^ 

HOCH2CH2NH2HCI + SOCI2— ^ 

CICH2CH2NH2HCI 

+ 

CICOOCH3 

i (la) 

CICH2CH2NHCOOCH3 

HOCH2CH2NH2 + CICOOCH3 — > 

HOCH2CH2NHCOOCH3 

+ 

SOCI2 (lb) 

\ 

CICH2CH2NHCOOCH3 

Methyl chloroformate may be prepared in good 
yield either by the addition of methanol to an excess 
of liquid phosgene or by the reverse addition 
of excess gaseous phosgene to methanol.^^’" The 
second alternative gives better yields based on 
methanol. An excess of phosgene is required to mini- 


SECRET 


115 


116 


ALIPHATIC NITROSOCARBAMATES AND RELATED COMPOUNDS 


Table 1. Aliphatic nitrosocarbamates and related compounds examined as candidate chemical warfare agents. 

The compounds are arranged in four major categories in the following sequence: (1) nitrosocarbamates, (2) nitroso- 
amides, (3) nitrosoamines, and (4) miscellaneous carbamates. 

The following abbreviations are used: wuS refractive index at t C; d\ density in g/ml at t C; specific gravity at l\ C in 
reference to water at h C; mp, melting point in C; bpp, boiling point in C at p mm Hg; vph vapor pressure in mm Hg 
at < C; and voh, saturation concentration (volatility) in mg/1 at t C. 

Centigrade scale is used throughout. 


Compound 

Reference 

to 

synthesis 


Physical properties 

Property Reference 

Reference to 
toxicity 
data 

N itrosocarbamates 

1. Methyl N-methyl-N-nitrosocarbamate 

57 


1.44236 > 

48 

44 




1.2105 

48 

• . • 



bp^® 

59-60° 

48 


2. Ethyl X-methyl-N-nitrosocarbamate 

Commercial 


1.43632 

60 

10 



1.1402 

56 




bp^^ 

65-65.5° 

60 

* 

3. /3-P4uoroethyl N-methyl-N-nitrosocarbamate 

21b 

bp^ 

70-80° 

21e 

10 

4. /3-Chloroethyl N-methyl-N-nitrosocarbamate 

2 

bpO-2 

76-78° 

2 

10 

5. Ethyl N-ethyl-N-nitrosocarbamate 

Commercial 

bp22 

80-84° 


10 

6. Methyl N-(/3-chloroeth3d)-N-nitrosocarbamate 

2,21a, 23c, 43 

nu^^ 

1.4666 

41 

10, 41,44 



d:-^ 

1.3053 

41 




bpO.8 

72-76° 

2 

. . . 



vopo 

0.600 

11 

• . • 

7. Ethyl N-(/3-chloroethyl)-N-nitrosocarbamate 

2, 21a, 43 

bpio 

92-93° 

2 

10 

8. /3-Fluoroethyl N-(/3-chloroethyl)-N-nitrosocar- 


voB“ 

0.426 

11 


bamate 

21b 

bp-^ 

118-121° 

21c 

10 

9. Isopropyl N-(i3-chloroethyl)-N-nitrosocarbamate 

2 

bpO.5 

80° 

2 

10 

10. Butyl N-(/3-chloroethyl)-N-nitrosocarbamate 

2 

bpO.6 

95° 

2 

10 

11. Method N-(,i3-bromoethyl)-N-nitrosocarbamate 

2 Id, 54c 

bp^ 

110-115° 

21d 

10, 44 

12. Methyl N-(i8-hydroxyethyl)-N-nitrosocarbamate 

2 

bpO.9 

90-95° 

2 

10 

13. Methyl N-(/3-chloropropyl)-N-nitrosocarbamate 

2 

bpO.3- 

75-80° 

2 

10 

14. Methyl N-butyl-N-nitrosocarbamate 

15. Methyl N-)8-(/3'-chloroethylthio)-ethyl-N-nitroso- 

2 

bp-^ 

70-72° 

2 

10 

carbamate 


. . . 


• . . 

44 

16. Methyl N-phenethyl-N-nitrosocarbamate 

21d 

Cannot be distilled 

21d 

10 

N itrosoamides 

17. N-( /3-Chloroet hy 1 )-N-ni t rosof ormamide 

2 

bpO.8 

78-80° 

2 


18. N-( /3- Chloroet hyl )-N -nit rosoacet ami de 

2 

bp 0.5 

70-72° 

2 

10 

19. N-Met hy 1-N -nit rosofluoroace tamide 

51 

bpi4 

84° 

51 

50 

Nitrosoamines 

20. N-Nitrosopiperidine 

2 

bpi^ 

94-96° 

2 

10 

21. N-Nitrosomorpholine 

2 

mp 

28° 

2 

10 



bpi4 

105-107° 

2 

. . . 

22. N,N'-Dinitrosopiperazine 

2 

mp 

155-157° 

2 


23. )3-Chloroeth5dmethylnitrosoamine 

54b 



. . . 

44 

24. 6fs(i8-Chloroethyl)nitrosoamine 

2 

Cannot be distilled 

2 

10, 44 

25. 4-Methyl-4(methylnitrosoamino)-pentanone-2 

20. N,N '-Dimethjd-NjN '-dinitroso-p-phenylene- 





10 

diamine 

27. N,N'-6/s(/3-Chloroethyl)-N,N'-dinitroso-p-phenyl- 

15 

mp 

149-150° 

15 

10 

enediamine 

15 

mp 

106.5° 

15 

10 

Miscellaneous carbamates 

28. Methyl N-(/3-chloroethyl)-N-nitrocarbamate 

2 

bpO.3 

95-100° 

2 

10 



vopo 

0.138 

11 


29. Methyl N-/3-chloroethylcarbamate 

2 


1.4575 

27 

10, 44 



bpi4 

100° 

2 

. . . 

30. Ethyl N-isobutylcarbamate 

15 

bpi6 

94° 

15 

10 

31. Ethyl N-isoamylcarbamate 

15 

ni)2o 

1.4333 

15 

10 


. . . 

bp'6 

109° 

15 

. . . 

32. Phhyl N-methoxycarbamate 



— 


10 


SECRET 


SYNTHESIS AND PROPERTIES 


117 


Table 1 {Continued). 

Compound 

Reference 

to 

synthesis 


Physical properties 

Property Reference 

Reference to 
toxicity 
data 

33. Methyl X-ethylthiolcarbamate 

12 

ni)2®-5 

1.4978 

12 

10 




1.078 

12 




bp29 

118° 

12 




bp3® 

123° 

12 


34. Methyl X-ethylthionocarbamate 

12 

ni>25 

1.5150 

12 

10 



d2o 

1.067 

12 




bp25 

109.5-110.5° 

12 




bp*^ 

119-121.5° 

12 


35. Methyl X-ethyldithiocarbamate 

12 


1.6139 

12 

10 




1.151 

12 




bp^ ® 

121-122° 

12 



mize formation of methyl carbonate. Distillation of 
the crude methyl chloroformate is not necessary.**^ 

2. Preparation of KB-16 by nitrosation of methyl 
N- (/3-chloroe thy 1) carbamate. This step may be ef- 
fected by nitrous acid in solution or by nitrous gases 
either with or without a solvent. The action of ni- 
trous gases on methyl N-(j8-chloroethyl) carbamate 
in the absence of a solvent is the most rapid and 
convenient. 

HNOi or 

CICH 2 CH 2 NHCOOCH 3 r ^ 

nitrous gases 

C1CH2CH2N(N0)C00CH3 ( 2 ) 

Reaction (la) was employed in the original labo- 
ratory preparation of KB-16. i8-Chloroethylamine 
hydrochloride prepared essentially according to 
Ward from solid ethanolamine hydrochloride and 
thionyl chloride in chloroform was treated as a solid 
suspended in ether or benzene with aqueous alkali 
and methyl chloroformate. The resulting methyl 
N-(iS-chloroethyl)carbaniate was purified by distilla- 
tion, diluted with ether or benzene, mixed with a so- 
lution of sodium nitrate, and nitrosated by the addi- 
tion of nitric or sulfuric acid. Overall yields of 62 per 
cent were obtained. Alternatively, N-(i8-chloro- 
ethyl) carbamate was nitrosated under anhydrous 
conditions by the use of nitrous gases. Flash distilla- 
tion was used to purify the final product and appears 
to be the only feasible method. The above procedures 
were used with little modification for the synthesis of 
the first samples investigated in Great Britain. 
The method is well suited for large-scale runs. 

Preparation of KB-16 by the alternative procedure 
utilizing reaction (lb) is also convenient for labora- 
tory scale work and can be carried out in overall 
yields of 65 per cent.'*^’'^^ It is less readily modified 
for use on a larger scale because the hydroxy car- 


bamate must be distilled and the conversion of this 
intermediate to the chloro compound has not been 
achieved in yields greater than 75 per cent. 

The first method, as modified for production on a 
larger scale, has been simplified by: (1) elimination 
of the isolation of ethanolamine hydrochloride and of 
jS-chloroethylamine hydrochloride, both of which are 
hygroscopic ; (2) combination of the first three steps 
into one; (3) reduction of the large excess of thionyl 
chloride and sodium nitrite; (4) the use of a single 
solvent (chloroform or benzene) in reduced quantity 
throughout the reaction steps; and (5) elimination 
of all distillations except that of the methyl N-(iS- 
chloroethyl) carbamate. A brief description of 

the modified process follows. Ethanolamine in chloro- 
form,'*® in benzene,^^® or in the absence of a solvent ^ 
is treated with dry hydrogen chloride to produce 
ethanolamine hydrochloride. Thionyl chloride is then 
added directly (if no solvent was used in the first 
step, benzene is added at this point), and the mixture 
is heated to convert the ethanolamine hydrochloride 
to i3-chloroethylamine hydrochloride. The mixture is 
then diluted with water, and caustic alkali and 
methyl chloroformate are added. After the acylation 
is complete, the organic layer is separated, washed, 
dried, and stripped of solvent. The crude methyl 
N- (/3-chloroe thy 1) carbamate thus obtained is then 
distilled under diminished pressure. It has been ob- 
tained in yields of 77.5 per cent in runs utilizing 
24.5 lb of ethanolamine. 

If nitrosation is carried out by slowly acidifying a 
mixture of the carbamate in benzene or ether with an 
aqueous nitrite solution, the reaction is slow and a 
large excess of sodium nitrite is necessary When 
the reverse addition is used and the reaction mixture 
is strongly acid, a slight excess of sodium nitrite is 
sufficient and the reaction proceeds rapidly.^® 


SECRET 


118 


ALIPHATIC NITROSOCARBAMATES AND RELATED COMPOUNDS 


Aqueous nitrosations were used in all investiga- 
tions where scaling up the synthesis of KB- 16 was 
tried, but it was subsequently shown that the re- 
action of nitrous gases with methyl jS-chloroethyl- 
carbamate in the absence of a solvent is quantitative 
and almost instantaneous.^^® This variation pos- 
sesses a number of practical advantages. 

1. Solvent is eliminated and effective reactor ca- 
pacity is thereby increased. 

2. The purity of the final product is sufficient to 
obviate the need for flash distillation. 

3. Equipment is simplified and the total time 
cycle is reduced. 

4. The method should allow preparation of the 
agent in situ shortly before use, or in shell subsequent 
to firing. This would eliminate the problem of storage 
stability and greatly lessen the hazards involved in 
synthesis. 

Preliminary design data and cost estimates for a 
plant to produce KB- 16 at the rate of 500 tons per 
month have been submitted. The calculations were 
based on the use of aqueous nitrosation in the final 
step.® 

N-(/3-Chloroethyl)-N-nitrosoacetamide, a highly 
toxic analog of KB- 16, has been prepared on a labora- 
tory scale by nitrosation of an ethereal solution of 
N-(/3-chloroethyl) acetamide with oxides of nitrogen. 
Yields of 60 per cent of material purified by flash 
distillation were obtained. ^ 

8.2.2 Physical Properties 

KB-16 is usually obtained as an orange-red limpid 
oil of limited thermal stability. It is soluble in water 
to the extent of 0.7 g/100 g, and is completely misci- 
ble with ordinary organic solvents. Although it has 
not been obtained in crystalline form, it assumes a 
semisolid state at — 65 C; at — 25 C it is a viscous oil. 

The density of KB-16 is 1.3053 g/ml at 25 the 
refractive index 1.4685 at 25 and the boiling 
point 100 C at 15 mm, 89 C at 6.5 mm^ 86 C at 
5.5 mm, 82 C at 4 mm, and 75 C at 2 mm.^^ 

The volatility of KB-16 is 0.87 mg/1 at 25 C, 
slightly less than the corresponding value of 0.96 
mg/1 for 5fs(/3-chloroethyl) sulfide (H). Several de- 
terminations of the volatility (or vapor pressure) as 
a function of temperature have been made.^’^^’^^ The 
vapor pressure at temperatures in the range of inter- 
est for chemical warfare is given by the following 
equation : 

2959 3 

log p (mm Hg) = 8.91282 


The standard free energy of formation of KB-16 
and several thermodynamic constants of the inter- 
mediate carbamate have been calculated from the 
results of a series of calorimetric and equilibrium 
studies.'^ 

8.2.3 Chemical Properties 

KB-16 decomposes within 48 hours in water or in 
aqueous bicarbonate solutions.^ In the former case 
about 40 per cent of the nitrogen appears as nitric 
acid, the remainder disappearing from the reaction 
mixture. Only 5 per cent of the chlorine appears as 
chloride ion. In bicarbonate solution more than 90 
per cent of the nitrogen is lost, presumably as nitro- 
gen gas, and carbon dioxide and methanol are pro- 
duced. About 30 per cent of the chlorine appears as 
chloride ion; the remainder is bound to carbon, pre- 
sumably in the form of ethylene chlorohydrin. The 
production of chloride ion at pH 8 is not significantly 
altered in the presence of substances which react 
with the /3-chloroethyl groups of the sulfur and nitro- 
gen mustards. The decomposition of ethyl N-(i3-chlo- 
roethyl)-N-nitrosocarbamate in aqueous solutions is 
similar to that of KB-16. ^ 

One of the most characteristic reactions of KB-16 
is its rapid and complete decomposition with evolu- 
tion of nitrogen when treated with alcoholic ammonia 
or primary aliphatic amines.^ Solutions of ammonia 
or ethanolamine in ethylene glycol have therefore 
been recommended as personal or laboratory decon- 
taminants.- However, the distinct possibility that 
substances of the nitrogen mustard type may be 
formed by this reaction should be considered in the 
choice of a decontaminant (see below). Secondary 
amines and primary aromatic amines react relatively 
slowly with KB-16. 

In aqueous solutions, the reaction with ammonia 
and with primary amines is slower, perhaps because 
of the low solubility of the nitrosocarbamate. At 
pH 8, the main reaction with primary amino groups 
is carboalkoxylation, as has been demonstrated by 
the isolation of methyl and ethyl N-benzylcarba- 
mates as products of the reaction of benzylamine 
with methyl and ethyl N-(/3-chloroethyl)-N-nitroso- 
carbamates, respectively.® Secondary amines (di- 
ethanolamine) are also carboalkoxylated. 

In ethereal solution, reaction with benzylamine 
leads to methyl N-benzylcarbamate and N,N'-di- 
benzylethylenediamine, the latter probably arising 
through benzyl-jS-chloroethylamine as an inter- 
mediate.® 


SECRET 


SYNTHESIS AND PROPERTIES 


119 


The amino groups of a-amino acids also react with 
KB-16, but the reaction is more sluggish than those 
of primary aliphatic amines and does not appear to 
go to completion. With cysteine, the reaction pro- 
ceeds along several lines; both amino and sulfhydryl 
groups disappear. 6zs-S-(Cysteinyl) ethane, probably 
arising through the intermediate S-(/3-chloroethyl)- 
cysteine, has been isolated as a product of this re- 
action.^ Nitrosome thy lure thane also carbethoxylates 
the amino group of cysteine, but is far less active 
toward the sulfhydryl group than is KB-16. ^ 

In solutions containing egg albumin KB-16 reacts 


/?-chloroethyl group into amines and into the sulf- 
hydryl compounds. The intermediate products are of 
the sulfur and nitrogen mustard type, and undergo 
further reactions characteristic of these substances 
(see Chapter 19). 

With regard to loci of action in tissues, it may be 
noted that reactions of the sulfur and nitrogen mus- 
tards involve a process of thermal solvolytic activa- 
tion in water (see Chapter 20). On the other hand, 
the alkylation of benzylamine by KB-16 in ether so- 
lution demonstrates that this agent need not be so 
activated. As a result, it is possible that KB-16 can 


ClCHz- CH2- N(N 0 ) . CO - OCH3 







+ H 2 O at pH 8 

+ RNH 2 

-h HS.CH2.CH(NH2).C00H 



ClCHo . CH 2 NH + HO . CO . OCH 3 CICH 2 . CH 2 . NH + R . NH . CO . OCH 3 CICH, • CH 2 NH + HS • CH 2 • CH • COOH 


NO 
- H2O 


k. 


ro 

- H2O 


CICH2 • CHN2 CO2 + HOCH3 ClCHo- CHNo 


+ H2O 
CICH2CH2.OH + N2 


+ R.NH2 

CICH 2 .CH 2 .NH.R + N 2 
+ RNH2 

R.XNH.CH 2 CH 2 NH.R + HCl 


NO 
- H2O 


I 

NH.COOCH3 


CICH 2 CHN 2 


+ HS.CH2-CH(NH2).C00H 

C1CH2.CH2SCH2CH(NH2)C00H + N 2 
+ HSCH2CH(NH2)C00H 

COOH COOH 

CH.CH2SCH2CH2S*CH2CH + HCl 
NH 2 NH 2 


slowly with the liberation of 1 mole of nitrogen per 
mole of nitrosocarbamate but no decrease in the 
amino nitrogen content of the protein occurs.^ The 
reaction with hemoglobin is rapid and in this case 
some amino groups disappear, possibly by carbo- 
methoxylation, although it has not been possible to 
ascertain the mode of reaction.^ 

The following scheme of reaction, reminiscent 
of those of Klobbie and V. Pechmann for the 
breakdown of nitrosomethyl- and nitrosoethylur- 
ethanes, has been proposed to explain many of the 
observed reactions of KB-16. ^ Thus KB-16 can be- 
have as a chloroalkylating agent, introducing the 


react in fatty phases of tissues, whereas reactions of 
the nitrogen mustards in these loci are not equally 
probable.* 

8 . 2.4 Detection and Analysis 

KB-16 reacts with the DB-3 reagent to produce 
the characteristic blue color. Samples as small as 
25 Mg may be detected by use of the DB-3 tube of the 
United States Army M-9 Detector Kit according to 
the standard procedure. By heating to 200 C, the 
sensitivity of the tube can be increased sufficiently 
to permit the recognition of 1 Mg-^® In the absence of 
a guard tube, the spotted dick test of the British 


SECRET 


120 


ALIPHATIC NITROSOCARBAMATES AND RELATED COMPOUNDS 


Vapor Detector Kit gives an overall blue color.'^^ 
Acidified iodoplatinate paper is bleached by the 
vapor of the agent. Other procedures for detection 
involve the use of the diethylamine and diphenyl- 
benzidine reagents or the Liebermann reaction. 
Positive reactions given by the decomposition 
products of KB- 16 limit the usefulness of these 
methods. 

The most useful method for the analysis of KB- 16 
depends upon the quantitative evolution of nitrogen 
which occurs when the compound is treated with 
primary amines or with alcoholic alkali. This 
method is suitable for use as an assay method or for 
analysis of samples collected in chamber or field 
tests, and has the advantage of specificity to the ex- 
tent that it measures only the nitrosated material. 
The Griess reagent as used for nitrites can be em- 
ployed for the field or chamber analysis of this 
agent.'*^ 

A more detailed discussion of the detection and 
analj^sis of the nitrosocarbamates will be found in 
Chapter 34. 

8.2.5 Stability 

KB-16 and its homologous esters are thermally un- 
stable. Decomposition with gas evolution occurs at 
rates which make storage impractical.^ '*^ In steel 
containers with 25 per cent void, the pressure in- 
crease per day is appreciable at temperatures as low 
as 4 C and amounts to about 2 psi at room tempera- 
ture.^ At high temperatures the decomposition be- 
comes even more rapid, the pressure increase in glass 
with 50 per cent void amounting to about 4.5 psi per 
day at 60 C."** No significant difference between the 
rates of pressure development in glass and steel con- 
tainers has been observed (unpublished data), even 
though steel appears to be attacked.'** The purity of 
the sample has a considerable effect on the rate of 
thermal decomposition, carefully purified material 
decomposing at a lower rate than crude material. 
The stability of preparations made by nitrosation 
with nitrous gases is as good as or better than that of 
flash-distilled samples. Decomposition is accelerated 
by acidic and phenolic substances and by zinc and 
magnesium oxides.^ There is disagreement as to 
the effect of traces of water, weak bases, or contact 
with metals other than steel. ^ '** 

The gas produced during the decomposition of 
KB-16 consists principally of nitrogen; oxides of 
nitrogen, carbon dioxide, and hydrogen chloride 
have also been identified.*®** 


In spite of intensive searches for a stabilizer to 
prevent or minimize the spontaneous decomposition 
of KB-16, little success has been achieved. Few of the 
tested substances were of any value and none pro- 
duced a pronounced increase in storage stability. 
The tested compounds include organic and inorganic 
bases, acids and derivatives of acids, hydroxy and 
mercaptan derivatives, oxidizing agents, inert liquids 
and solids, salts and complexes of heavy metals, and 
numerous miscellaneous compounds.^^‘=’'** 

Few reliable data are available on the stability of 
KB-16 to detonation in munitions. *®"*’^®’^*’'** The re- 
sults of a field trial wdth 105-mm shell supply no 
definitive information.®® In a small chamber, detona- 
tion of a 75-mm shell charged KB-16 resulted in 
more or less complete destruction of the agent;®* in 
similar tests ethyl-6fs (jS-chloroe thy 1) amine (HNl) 
was also destroyed but ^m(jS-chloroethyl) amine 
(HNS) was not. It may be noted that the conditions 
of these tests w^ere more severe than would be en- 
countered in the field, and that HNl can effectively 
be dispersed from M47A2 bombs.^* KB-16 is not de- 
stroyed to any great extent by the milder explosions 
that occur wKen it is dispersed from glass bottles 
either in the field by means of a standard detonator ®* 
or in a 2-cu m chamber by means of a blasting cap or 
detonator.*®***’®* 

8.2.6 Decontamination 

Rapid surveys of the reactions of KB-16, with 
emphasis on reactions of possible use in decontamina- 
tion, have been carried out both in this country and 
in Great Britain. 2 ® -'*7 The reagents examined included 
bleaching powder, chloramides, a number of inor- 
ganic salts in solution, mineral and organic bases, at 
least one strong oxidizing agent, and reducing agents. 
Solid bleach or lime slurry would appear to be suit- 
able for field use. Caustic soda or alcoholic ammonia 
has been recommended for laboratory use, and aque- 
ous ethanolamine for personal use. In line with these 
recommendations, groups concerned with the synthe- 
sis of the agent have used solutions of ammonia or 
ethanolamine in alcohol or ethylene glycol for per- 
sonal, laboratory, and pilot plant decontamina- 
tion. 2 *^®^ As stated above, ammonia or primary 
amines should be used with caution because of the 
possibility of producing toxic intermediates.® 

For treatment of eyes contaminated with KB-16, 
mild alkalies and reducing agents (e.g., BAL) should 
be more effective than in the case of nitrogen mus- 
tards.^® 


SECRET 


CHEMICAL STRUCTURE IN RELATION TO TOXICITY 


121 


8.2.7 Protection 

The canisters of modern gas masks afford ade- 
quate protection against the vapor For 

details the reader is also referred to the Summary 
Technical Report of NDRC Division 10. 

The chloramide impregnation of clothing would 
appear to offer little resistance to KB- 16, because 
this agent fails to react with chloramine-T or with 


various impregnites.^® It may be assumed that cloth- 
ing containing activated carbon would effectively 
exclude the vapor of the agent. 

8.3 CHEMICAL STRUCTURE IN RE- 
LATION TO TOXICITY 

In Table 2 are presented data on the toxicity for 
mice of compounds in which the N-nitroso, N-(j(3- 


Table 2. To.xicities of N-substituted aliphatic carbamates for mice. 

Most of the data are taken from reference 10. The mice were observed for 10-15 days after exposure for 10 minutes to 
the stated nominal concentration. In the case of one compound, methyl N-methyl-N-nitrosocarbamate, the data were 
obtained from reference 48 and relate to rats exposed for 30 minutes. 


Compound 

The prototype compound 

Methyl N-(i3-chloroethyl)-N-nitrosocarbamate (KB-16) 


Effect of replacement of the N-nitroso group 
Methyl X-(/3-chloroethyl)carbamate 


Methyl N-(/3-chloroethyl)-N-nitrosocarbamate 


Ethyl X-(/3-chloroethyl)-X-nitrosocarbamate 


Ethyl X,X-h?s(/3-chloroethyl)carbamate 


,X-(/3-chloroethyl)-X-nitrosoacetamide 


X,X-6f8(/3-chloroethyl)acetamide 


Effect of replacement of the N -{^-chloroethyl) group 
Methyl X-methyl-X-nitrosocarbamate 


Methyl X-((3-bromoethyl)-X-nitrosocarbamate 


Mortality 

Structural Xominal cone. for 10-min 

formula (mg/1) exposure 


CICH2CH2 O 

^X— C— OCH3 

/ 

OX 


CICH2CH, o 

\ II 

X— C— OCH3 

/ 

H 

CICH2CH2 O 

^X— C— OCH3 

/ 

O2X 

CICH2CH2 o 

^X— C— OC2H5 


ox 

CICH2CH2 o 


C1CH2CH2 

C1CH2CH2 


X— C— OC2H5 

/ 

o 

s II 

X— C— CH3 


ox 

CICH2CH2 o 

N — C — CH 3 

C1CH2CH2'^ 


0.036 


1.0 


1.3 


0.075 


0.4 


0.046 


0.5 




0/20 


0/20 


LCso 


0/40 


LC50 


0/10 


CH3 O 

\ 1 ! 

X— C— OCH3 0.26 (30 min) ^ (rats) 

/ 0.13 (30 min) ^ (rats) 

ON 

BrCHoCH2 O 

\ II 

X — C — OCH3 0.2 0/10 

/ 0.82 10/20 

OX 


SECRET 


122 


ALIPHATIC NITROSOCARBAMATES AND RELATED COMPOUNDS 


Table 2 {Continued). 


Compound 

Structural Nominal cone, 

formula (mg/ 1 ) 

Mortality 
for 10 -min 
exposure 

Methyl N-(/3-hydroxyethyl)-N-nitrosocarbamate 

HOCH 2 CH 2 0 



Methyl N-(| 8 -chloropropyl)-N-nitrosocarbamate 

"X II 

N— C— OCH 3 

ON^ 

CH. 3 CHCICH 2 0 

0.3 

0/20 

Methyl N -buty 1-N -n i trosocarbamate 

\ II 

N— C— OCH 3 

ON^ 

CH 3 CH 2 CH 2 CH. 0 

\ II 

0.3 

0/10 

Methyl N-phenethyl-N-nitrosocarbamate 

\ II 

N— C— OCH 3 

ON'^ 

CfiHo— CH 2 CH 2 0 

^N— C— OCH 3 
ON^ 

CICH 2 CH 2 0 

0.3 

1/20 

Effect of replacement of the methoxy group 

Ethyl N -jS-chloroethy 1-N -n i trosocarbamate 

0.97 

0/20 


\ || 

N— C— OCH 2 CH 3 

ON^ 

0.075 

LC50 

/3-Fluoroethy 1 N -(/S-chloroethy 1)-N -nitrosocarbamate 

CICH 2 CH 2 0 

0.1 

11/15 

\ II 

0.2 

11/20 


N— C— OCH 2 CH 2 F 

ON^ 

0.5 

10/20 

Isopropyl N-(/3-chloroethyl)-N-nitrosocarbamate 

CICH 2 CH 2 0 

0.1 

6/20 

"^N— C— 0CH(CH3)2 
ON^ 

CICH 2 CH 2 0 

0.12 

20/20 

Butyl N-(/3-chloroethyl)-N-nitrosocarbamate 

0.2 

16/18 


\ II 

N— C— OC4H9 

0.16 

LC50 

N-(/3-chloroethyl)-N-nitrosoacetamide 

ON^ 

CICH 2 CH 2 0 

\ II 

0.44 

LCso 


\ II 

N— C— CH 3 

on"^ 

0.046 

LC50 


chloroethyl), and methoxy groups of KB- 16 are re- 
placed by other substituents. On the basis of these 
data, and subject to their limitations, the following 
conclusions can be drawn. 

1. The N-nitroso group is essential for high toxic- 
ity. Its replacement by another group has always re- 
sulted in at least a 30-fold reduction in toxic potency. 

2. The N-(/8-chloroethyl) group is essential for 
highest toxicity, but moderate toxicity is possessed 
by some compounds in which it is replaced by an 
alkyl group (e.g., ethyl N-methyl-N-nitrosocarba- 
mate apparently possesses one- tenth the potency of 
ethyl N - (/3-chloroethy 1) -N -ni t rosocarbama te) . 


3. The methoxy group, although optimal, is not 
essential for high toxicity. Its replacement by a 
methyl group (to form N-(i8-chloroethyl)-N-nitro- 
soacetamide) results in an insignificant decrease in 
potency, and the ethoxy analog is about one-half as 
toxic as KB-16. 

Toxicity data for other species, vesicancy tests, 
and determinations of eye-injuring potency are not 
sufficiently complete to permit analyses of the rela- 
tive potencies of members of this series. Such data 
as are available indicate the relative superiority of 
KB-16 and are not inconsistent with the other con- 
clusions drawn from the toxicity tests with mice. 


SECRET 


TOXICOLOGY 


123 


Compounds which possess a fluoroacetate-like toxic- 

O 

II 

ity by virtue of the presence of an FCH 2 C — group 
are an exception to this generalization (see Chap- 
ter 10). 

8.4 TOXICOLOGY 

Of the following toxicological sections, those on 
detectability by odor and sensory irritation, vesi- 
cancy, and eye-injuring action bear most directly on 
the evaluation of KB- 16 and related compounds as 
chemical warfare agents. 

8.4.1 Detectability by Odor and 
Sensory Irritation 

The vapor of KB- 16 has a pleasant odor, some- 
times described as sweet or fruity, which can be de- 
tected by smell only at concentrations several times 
greater than those required for H. Men exposed to 
relatively high concentrations (i.e., 70 /zg/1 nominal) 
for 30 seconds detect the odor but experience no 
sensory irritation,'*^ and concentrations as high as 
0.2-0. 4 mg/1 elicit no signs of irritation in animals.*®*^ 
These properties of KB-16 vapor, considered in rela- 
tion to its eye-injuring potency and the delayed on- 
set of the injuries caused by casualty-producing 
dosages (see the following section), confer upon it 
some insidiousness. However, in this regard it is not 
notably superior to some of the nitrogen mustards 
(e.g., HN3), which are probably less easily detected 
by odor and not notably inferior in eye-injuring 
potency (see Chapter 6). 

Laboratory determinations of the median de- 
tectable concentrations in /xg/l of KB-16, H, 
ethyl-6fs(/3-chloroethyl)amine (HNl), and HN3 are 
tabulated below. Attention is directed primarily to 
the relative values, inasmuch as the absolute values 
are not necessarily of significance for field conditions. 



Agent 

Mg/1 

Reference 

H 

Plant run Levinstein 

0.6 

34 


Pure thiodiglycol 

1.8 

35 

KB-16 


7± 

16 1, 41 

HNl 

Plant run 

13 

34 


Pure 

17 

33 

HNS 

Plant run 

15 + 

37 

• 


The vapor of N-(i(3-chloroethyl)-N-nitrosoaceta- 
mide does not possess the insidiousness of KB-16.*®*’*^j 


8.4.2 Toxicity 

Inhalation Toxicity 

In Table 3 data on the toxicity of KB-16 vapor 


Table 3. Inhalation toxicity of KB-16 in comparison 
with mustard gas (H) and <m()8-chloroethyl)amine (HNS). 


Approximate nominal LC50 in mg/1 for 10-min 
exposure and 15-day observation period.* 


Species 

KB-16 

H 

HN3 

Mouse 

0.036 (259)p-i«« 

0.12i'i6*.‘* 

0.12§i6* 

Rat 

0.1-0.2 (19)16^ 

0.035 (60y 

0.1161.P 

Q 2-16g,o.22d 

Guinea pig 

0.2 ± (17)i6b 

0.2-16* 

>0.2168 

Rabbit 

>0.2 (7)'-i6b.4i 

0.28138 

0.1416® 

Cat 

0. 1-0.2 (ll)i6b.i 

0.0716* 

0.0816*'.“ 

Dog 

0.1 (14y6b.j.l7d 

0.0716* 

Q pek ,0,65 

Goat 

0.3 (6)i7d 

0.19t36 


Monkey 

0.2-0.5 (6)i'd 

0.0816P 



* In the case of KB-16 some deaths occurred among the larger species 
after observation periods as long as 15-30 days and were included in esti- 
mating the LCso’s. 

t The figures in parenthesis give the number of animals upon which the 
estimated LCbo’s are based. 

t Analytically determined concentration. 

§ The analytical LCbo is about 0.055 mg/1. 

for various animal species are set forth in comparison 
with corresponding data for H and HN3. One of the 
early observations arousing interest in KB-16 was 
the discovery that for mice it is several times more 
toxic than H. When tests were made with other spe- 
cies, however, no such differential in favor of KB-16 
was found, except possibly in the case of the rat. In- 
deed, it may be questioned whether KB-16 is as toxic 
as H for the larger mammalian species which have 
been studied. 

The only evidence bearing on the relation of tox- 
icity of KB-16 to exposure time is the demonstration 
that the L{Ct)^Q for mice is approximately the same 
for 30-minute exposures as for 10-minute expo- 
sures,*®*" and the result of a single experiment in which 
a dog succumbed 23 days after exposure to a total 
vapor dosage of approximately 1,100 mg min/m® 
administered during three 8-hour periods on suc- 
cessive days.*^^* 

During exposure to KB-16 vapor at concentra- 
tions as high as 0. 2-0.4 mg/1, animals exhibit no 
signs of discomfort or irritation.*®*" Concentrations 
considerably in excess of the 10-minute LC. 5 o’s occa- 
sionally caused closing of the eyes, but the irritation 
was mild and not accompanied by profuse lacri- 
mation. 

The development of symptoms after gassing with 
KB-16 is usually delayed for 12-24 hours and follows 
the same general pattern in different species.'* ’*®*"’*'*‘* 
Respiratory distress becomes prominent. The ani- 
mals appear depressed and stop taking food and 
water; as a consequence weight loss may be precipi- 


SECRET 


124 


ALIPHATIC NITROSOCARBAMATES AND RELATED COMPOUNDS 


tous. Severe eye injuries also develop (see Sec- 
tion 8.4.4). In nonfatal cases the symptoms slowly 
subside. In fatal cases respiration may become la- 
bored and terminate in death after 3-10 days, or the 
animals may slowly waste away and die as late as 
3-4 weeks after exposure. 

The principal pathological changes occurring in 
animals gassed with KB- 16 are found in the eyes 
(see Section 8.4.4) and the respiratory tract.'‘'^®^'"’^'^® 
In mice the most severe changes are confined to the 
nasal and nasolaryngeal mucosa, and an exudate, 
first fluid and later mucopurulent, is often produced 
in sufficient amount to block the air passages. The 
trachea and bronchi show much less damage. The 
lungs may become hyperemic but pulmonary edema 
is minimal and pneumonia does not ordinarily de- 
velop. In larger species, perhaps because the larger 
size of the air passages permits further penetration 
of the vapor, nasal injury is accompanied by severe 
pathological changes in the deeper parts of the respir- 
atory system. The larynx, trachea, and bronchi are 
severely involved, and pulmonary injury with con- 
solidation occurs. The pneumonia often appears in 
focal patches around the bronchi. Degenerative ma- 
terial cast off from the larger respiratory tubes often 
blocks some of the larger and smaller bronchial pas- 
sages. 

In general the bone marrow is little affected. 
Atrophy of the lymphoid organs with rhexis of the 
lymphocytes of the thymus gland and the splenic 
follicles has been reported in some species but was 
not found to be conspicuous in another investiga- 
tion.'* Hematological studies fail to reveal the con- 
spicuous changes in numbers of circulating white 
blood cells which characterize severe intoxication 
with the sulfur and nitrogen mustards, although a 
rise followed by a fall in lymphocyte count has been 
reported in mice exposed to about eight L{Ct)^Q 
dosages of KB-16 vapor. In some instances limited 
degenerative changes, possibly secondary to respira- 
tory embarrassment, have been observed in the liver 
and kidney. In mice and rats the digestive tract from 
upper esophagus to anus is often markedly distended 
with gas but no hemorrhages or perforations have 
been observed;'* the distention is probably caused 
by swallowing of air, which occurs because of mouth 
breathing and difficulty in respiration. 

The available data suggest that the principal 
pathological effects of ethyl N-(i8-chloroethyl)-N- 
nitrosocarbamate and of N-(/3-chloroethyl)-N-njtro- 
soacetamide are similar to those of KB-16. 


Toxicity through the Skin 

In its actions on and through the skin, KB-16 is 
relatively ineffective as a lethal agent when com- 
pared with H, HNl, or HN3. In spite of the high 
sensitivity of mice to the inhaled vapor, exposure of 
only the bodies of animals of this species to KB-16 
vapor at a nominal dosage of 6,900 mg min/m^ {t = 
10 min) caused no deaths within 15 days; 11,300 mg 
min/m^ killed 1/5 unshaved mice; and 13,000 mg 
min/m^ killed 6/6 mice with shaved backs. For 
other agents approximate nominal L(C0 5 o’s {t = 
10 min) for mice upon body only exposure are: H, 

4.000 mg min/m^; HNl, 5,000 mg min/m^; HN3, 

2.000 mg min/m^ (analytical value = 1,000); and 
L, 2,100 mg min/m^*^ The toxicity of liquid KB-16 
applied to the shaved skin of mice is also low when 
inhalation of vapor is minimized. Necrosis of the 
skin and ulcer formation occur at the site of appli- 
cation but a minimum value for the LD^q is believed 
to be 62 mg/kg. ^ Corresponding values for other 
agents are: H, 92 mg/kg; HNl, 13 mg/kg; HN3, 7- 
20 mg/kg (see Chapter 22) . It may be noted that all 
of these values are high in comparison with the per- 
cutaneous LD^q’s for some of the compounds con- 
sidered in Chapter 9. 

Toxicity by Injection 

Parenteral injections, although they have no direct 
bearing on chemical warfare, supply useful informa- 
tion concerning the toxicological properties of KB-16. 
LD^ds upon intravenous injection are: mouse, 0.45 
mg/kg; rat, 1.1 mg/kg; and rabbit, approximately 

2.0 mg/kg.'* The subcutaneous LD^o for the mouse is 

9.0 mg/kg; ^ and those for the rat and rabbit ap- 
proximately 8 and 20 mg/kg, respectively.^* Even 
large doses are without immediate pharmacological 
effects, and subsequent developments reveal no neu- 
rological injury, central nervous or gastrointestinal 
action, pronounced leucopenic action, or significant 
changes in the total number of circulating white 
blood cells.'* The conspicuous pathological changes 
occur in the lungs, which become distended, moist, 
and hyperemic. They sink in water and on cutting a 
pinkish, foamy fluid runs from the lungs and trachea. 
A small amount of pleural fluid accumulates. The 
heart is often dilated but gross pathological changes 
elsewhere are conspicuously absent. Venous con- 
gestion of the liver and myocardial injury with focal 
necroses are occasionally but not constantly ob- 
served. The thymus gland and spleen are usually but 
not markedly decreased in size — probably the re- 


SECRET 


TOXICOLOGY 


125 


suit of a nonspecific lymphoid involution. In some 
instances (e.g., in rabbits receiving large doses) there 
is evidence of lymphocytic fragmentation in the 
spleen, lymph nodes, and thymus. The bone marrow 
usually appears normal, although evidence of leuco- 
blastic stimulation appears in some rabbits.'‘ It has 
been reported that one of two dogs receiving 18 
mg/kg intravenously died in 4 days with aplasia of 
the bone marrow and drastic leucopenia, involving 
both lymphocytes and granulocytes.® It has been 
concluded that intravenously injected KB- 16 causes 
death by producing fatal pulmonary edema, which 
develops slowly over a period of 2-8 days.^ ® 

Injections by various routes demonstrate that 
KB- 16 reacts with liberation of gas (presumably N 2 ) 
in the first capillary bed it reaches.'* Circulatory 
stasis may occur, in some cases possibly because of 
vessel spasm or thrombosis, so that contact with the 
tissue may be prolonged. These observations give an 
explanation for the finding that the principal patho- 
logical changes following inhalation or intravenous 
injection occur in the lungs. The liberation of gas, 
which occurs in the tissues to which injected KB- 16 
is first carried and which also occurs when KB-16 is 
added to tissue suspensions, undoubtedly contributes 
ischemic injury to the chemical injury produced by 
the direct reactions of KB-16 with tissue compo- 
nents. The liberation of gas following inhalation of 
KB-16 vapor is presumably not sufficient to be sig- 
nificant. 

Toxicity by Mouth 

KB-16 is moderately toxic when administered by 
stomach tube. The LDso’s are in the order of 20 
mg/kg for the rat and 15 mg/kg for the rabbit.^* The 
substance is immediately irritating, as evidenced by 
vomiting in dogs, and it produces severe esophageal 
and gastric damage.*'® In the rat, vesicles similar to 
those produced by lewisite oxide have been found in 
the stomach at autopsy.'** Lung pathology has been 
observed in some cases *’® and the absorption of 
KB-16 from the gastrointestinal tract has been 
demonstrated by the appearance of gas bubbles in 
the hepatic portal vein.'* Death occurs after from 
one-half day to many days and is preceded by pro- 
nounced weight loss when survival is prolonged.*^®-'** 

That KB-16 presents some hazards as a water con- 
taminant is demonstrated by the virtually 100 per 
cent mortality of mice, rats, and dogs whose supply 
of drinking water was contaminated with 0. 5-1.0 
mg/ml. *^® Only few deaths occurred when the water 


was contaminated with 0.1 mg/ml. In most of the 
experiments the contaminated water was freshly 
prepared each day. In spite of the fact that aqueous 
solutions of KB-16 decompose within 48 hours (see 
Section 8.2.3), mice whose drinking water was con- 
taminated with 1.0 mg/ml of KB-16 at the beginning 
of one experiment died almost as quickly as those 
whose contaminated water supply was freshly pre- 
pared at daily intervals. 

8.4.3 Vesicant Action 

In comparison with H, the vesicancy of KB-16 is 
of a low order 14 . 41,46 ^nd screening tests indicate that 
none of the related compounds is more potent.*'* A 
direct comparison of “absolute vesicancies,” de- 
termined by application of agents diluted with ben- 
zene and covered to prevent evaporation, reveals 
that KB-16 is about to as potent as H.'** As 
shown in Table 4, small doses of liquid KB-16 applied 

Table 4. Vesicancy of KB-lG.i^ 

For the sake of comparison, data obtained with H and 
L are included. All applications of the vesicants were 
made during winter weather (January 1943) to the skin 
of the forearms of human subjects at room temperatures 
of 63-72 F and relative humidities of 14-37 per cent. 


Agent 

Dose 

(Mg) 

Days after 
applica- 
tion Erythemas 

Blisters 

KB-16 

200 

2 

7/28 

(4 mm) 

0/28 




7 

7/9 


1/9 

(2 mm) 

H 

65 

2 

112/119 

(7 mm) 

70/119 

(5 mm) 

L 

95 

2 

285/290 

(8+mm) 279/290 

(6 mm) 


to the skin in the usual way (i.e., undiluted and with 
evaporation permitted) produce far less injury than 
do H or L. Tested more realistically in relatively 
large doses (drops 1.1 mm in diameter), it produces 
injuries which after 3 days are no more severe than 
those elicited by HN3 or HN2.'*® It is known from 
other data (see Chapter 6) that, under the moderate 
conditions of temperature and humidity prevailing 
in the above test, these nitrogen mustards are no 
more than one-fourth as vesicant as H. All observa- 
tions *'*-'** ’'*®’®^® indicate that skin injuries due to 
KB-16 require considerably longer (i.e., 5-6 days) 
to attain maximum severity than do those usually 
produced under similar conditions by II, L, or the 
nitrogen mustards. 

It should be noted that all of the above observa- 
tions were confined to applications of the liquid agent 
to the not visibly sweating skin of physically inactive 
subjects at moderate temperatures and humidities. 


SECRET 


126 


ALIPHATIC NITROSOCARBAMATES AND RELATED COMPOUNDS 


No determinations have been made of the vesicant 
potency of liquid KB- 16 on hot, sweating skin, of the 
vapor under any conditions, or of the effectiveness of 
either the liquid or the vapor through ordinary or 
protective clothing. 

8.4.4 Eye-Injuring Action 

Numerous observations on the effect of KB-16 
vapor on human and animal eyes demonstrate that 
the agent is an insidious and potent eye-inju- 

mentioned, no exposure symptoms are produced in 
animals by even high concentrations (i.e., 0.2- 
0.4 mg/1), and exposures entirely undetected have 
sufficed to produce moderately severe injuries in 
laboratory workers. The onset of injury and ac- 
companying symptoms is more delayed than in the 
case of H, and much more delayed than in the case 
of the arsenicals. There is an asymptomatic latent 
period of many hours. Maximal damage develops 
after from two to several days, and recovery is pro- 
tracted. Corneal edema, opacity, and delayed but 
extensive vascularization are the most prominent 
symptoms. The conjunctivas are also injured, al- 
though less extensively than in the case of H. Iritis 
occurs but is not so conspicuous as in eyes exposed 
to HN2 or H. Delayed relapses such as occur in the 
case of H have not been observed. 

An interesting preliminary report indicates that, 
in addition to the injuries just described, severe 
retinal damage can be produced in animals by ex- 
posures to relatively small dosages of KB-16 vapor 
which produce only moderate conjunctivitis and 
slight and transient superficial keratitis. Changes in 
the retinas of cats examined 3-14 days after exposure 
of the animals to 0.05 mg/1 for 10 minutes consisted 
of: (1) slight increases in glial cells and perivascular 
macrophages, with hyperchromaticity of ganglion 
cells; (2) restricted zones of perivascular cuffing with 
leucocytes, resembling a periarteritis ; and (3) intense 
chorioretinitis with subhyaloid hemorrhages, migra- 
tion and phagocytoses of pigment, and extensive 
chromatolysis and destruction of ganglion cells. Com- 
parable exposures to HNl produced no morphologi- 
cal changes in the retinal ganglion cells, although 
clusters of leucocytes adhering to the endothelium of 
the blood vessels represented a difference from the 
normal retina. Exposures to H vapor (0.04 mg/1 for 
10 minutes) likewise produced the clustering of leuco- 
cytes, and in addition isolated small patches of cho- 
rioretinitis; however, changes in the neural elements 


were absent or at most mild compared with those 
produced by KB-16 at the slightly higher dosage. 

Data to be summarized in the following paragraphs 
lead to the conclusion that KB-16 vapor is a dis- 
tinctly more insidious eye-injuring agent than H 
vapor but not necessarily a more potent injurant 
when assessed on a dosage (Ct) basis. In this respect 
KB-16 is similar to HN3 (see Chapter 6). 

Exposure of Human Eyes to Small Dosages of 
KB-16 Vapor 

The eye injuries produced by the vapor of KB-16 
at small and minimal dosages may best be illustrated 
by citation of the case histories of accidentally ex- 
posed laboratory workers. 

In one case some KB-16 was splashed on the left side of 
the face. It was immediately decontaminated and the liquid 
presumably did not enter the eye, as the worker was wearing 
glasses. Nevertheless as a precaution the eyes were quickly 
washed with water. There were no ocular symptoms on the day 
of the accident. On the following day both eyes were slightly 
sore but normal duties could be carried out. Ophthalmic ex- 
aminations 3-22 days after the accident revealed the following 
effects. 3 days. The conjunctivas were hyperemic, the injection 
being more marked in the palpebral aperture than elsewhere. 
The cornea did not stain with fluorescein but scattered epi- 
thelial cells showed hydropic degeneration. The pupils were 
normal and there was no iritis. 4 days. The eyes were more un- 
comfortable and the patient experienced slight difficulty in 
keeping them open. The conjunctivas were more hyperemic 
and there was epithelial bedewing all across the palpebral 
aperture. All the limbal blood vessels were congested. The 
substantia propria of the cornea was normal. The lids were 
slightly swollen. There was no chemosis and no iritis. 5 days. 
The symptoms were worse and an attack of blepharospasm 
and photophobia occurred. Subepithelial cellular infiltrates 
could be seen in the left eye. 6 days. The congestion was worse 
and the left cornea still bedewed. 7 days. The patient felt that 
his sight was worse. Visual acuity was reduced from 6/12 (on 
the fourth day) to 6/24. The congestion was more marked and 
the superficial layers of the substantia propria were densely 
infiltrated with cells but not edematous. 9 days. The lids were 
slightly sticky and puffy, the conjunctivas very injected. The 
interior of the eyes was normal. 11 days. The limbal loops 
showed great activity and appeared to be advancing on to the 
corneas from all meridians. 16 days. The right eye was slightly 
better, the left showed further roughening of the epithelium 
and slight edema of the substantia propria. The limbal loops 
were advancing. 20 days. Photophobia persisted and the eyes 
appeared worse. Conjunctival injection was marked. The 
margins of both corneas were invaded with a rich superficial 
vascular net. The corneas were full of cells at all levels. 22 days. 
The limbal loops were still extending. The symptoms were 
somewhat alleviated but definite objective improvement had 
not started. Comment. The main points of interest are the 
absence of immediate symptoms, the long latent period, and 
the delayed recovery, even though the dose was insufficient to 
produce pupillary contraction or iritis. The prognosis was 


SECRET 


TOXICOLOGY 


127 


considered good in view of the course of the case next to be 
described. 

In a second case a chemist had been working with KB- 16 
for 3 days during which time he smelled nothing and experi- 
enced no sensation to suggest that he was being exposed to 
the vapor. On the second day his eyes were slightly bloodshot 
but not painful. On the evening of the third day of work he 
had a severe headache and pain in the eyes, and on awakening 
during the night found himself unable to keep his eyes open. 
He was examined at 3-22 days after he commenced his work. 
3 days. The lids were only slightly swollen but the patient was 
unable to keep his eyes open. There was lacrimation but no 
discharge. The conjunctivas were not very congested and there 
were no hemorrhages. In the palpebral aperture there was a 
band of epithelial edema and punctate staining. The pupils 
were small and their reaction to light poor. The patient had 
nasal discharge. 4 days. The eyes were still closed and the 
pain, now a gritty feeling, was relieved by phenacetin. The 
corneas appeared improved. The lids were slightly reddened. 
5 days. The gritty feeling persisted. There were no signs of 
iritis but the limbal loops were beginning to encroach on the 
corneas. 6 days. The eyes were much better and could be kept 
open for periods of an hour or more, with attacks of blepharo- 
spasm between. The conjunctival injection was almost limited 
to the palpebral apertures. The epithelium was bedewed but 
an ocular infiltration was beginning under Bowman’s mem- 
brane. The deep structures were normal. 7 days. The eyes 
could be kept open much better but lacrimation persisted. 
There were infiltrates throughout the substantia propria. 
9 days. Photophobia persisted and there was a slight whitish 
discharge. The epithelial bedewing in the palpebral apertures 
was less pronounced. The conjunctivas were still slightly in- 
jected. 11 days. The eyes were about as above except that new 
vessels were extending in open loops onto the corneas. Photo- 
phobia persisted. 15 days. The newly formed superficial vessels 
on the cornea were beginning to empty. 20 days. The photo- 
phobia had practically disappeared and the eyes were nearly 
normal on macroscopic examination. 22 days. The eyes were 
practically symptomless. The limbal loops had extended onto 
the cornea all around in both eyes but were mostly empty and 
disappearing. Subepithelial infiltrating cells were fewer, A 
few hydropic cells remained in a line on the palpebral fissure 
of one eye. Comment. The main points are that the exposure 
was unsuspected and symptoms delayed for 2 days. They 
then became severe. Virtually complete recovery had occurred 
within 22 days. 

A number of investigators working with KB- 16 
and presumably receiving minimal vapor dosages 
have developed mild ocular changes.^®® The conjunc- 
tivas showed at most only mild congestion. Exami- 
nation of the corneas revealed superficial punctate 
nebulae largely peripheral in location and almost al- 
ways confined to the interpalpebral area. The nebulae 
sometimes escaped detection on slit lamp examina- 
tion but were seen after fluorescein staining. Clini- 
cal notes also mention a Stahli’s line, unduly 
prominent corneal nerves but no alteration in corneal 
sensibility, and fine punctate hyaline areas best seen 


with lateral illumination or retroillumination and 
disappearing within 2-3 weeks. The observed changes 
were of a type commonly observed in various non- 
specific irritations of the eye and are difficult to 
evaluate. They were insufficient to produce signifi- 
cant subjective symptoms or loss of visual acuity. 
Nevertheless, in view of the slow development of the 
pathological changes caused by KB-16 vapor, it has 
been recommended that individuals showing such 
lesions avoid any possibility of further exposures for 
1-2 weeks. 

Comparison of KB-16 with Other Agents on 
Basis of Effects of Relatively Large Vapor 
Dosages on Animal Eyes 

Quantitative comparisons of the potencies of dif- 
ferent agents in terms of the dosages necessary to 
produce eye injuries of casualty severity are difficult 
at best and for KB-16 there exist no detailed quanti- 
tative studies such as have been made with Of 
the numerous interim studies with animals, two 
permit a more or less direct semiquantitative com- 
parison between the potencies of KB-16 and H. Both 
studies (Tables 5, 6, and 7) indicate that the poten- 

Table 5. Effects of the saturated vapors of KB-16 and 
H on the eyes of rabbits : effect of exposure time on sever- 
ity of injury. 24a 

The eyes were protopsed and exposed for the stated 
times at 22-24 C to vapor cups containing KB-16 or H, 
At 23 C the volatility of KB-16 is approximately 0.8 mg/1, 
that of H approximately 0.9 mg/l.^i The severity of the 
resulting lesions is tabulated. 


Exposure 



time 

Agent 

(sec) 

KB-16 

H 

15 

Mild conjunctival le- 

Minor conjunctival le- 


sion, slight corneal le- 
sion. Rapid recovery. 

sion. Rapid recovery. 

30 

Injury variable. Rare 

Injury variable. Com- 


perforation, occa- 
sional complete recov- 

plete recovery in 
most cases. 


ery. 


60 

Mild permanent dam- 

Moderate permanent 


age. Perforation in 

damage. No cases of 


some cases. 

perforation. 

120 

About same as 1-min- 

Severe damage. Many 


ute exposure. 

cases of perforation. 


cies of the two agents are of the same order of mag- 
nitude, the principal difference being that the onset 
of damage and possibly the rate of recovery are more 
delayed in the case of KB-16. In so far as this con- 


SECRET 


128 


ALIPHATIC NITROSOCARBAMATES AND RELATED COMPOUNDS 


Table 6. Effects of the saturated vapors of KB-16 and 
H on the eyes of rabbits: tabulation of types and relative 
severities of in juries. 2*^ 

The eyes were protopsed and exposed for 1 minute at 
22-24 C to vapor cups containing KB-16 or H. At 23 C 
the volatility of KB-16 is approximately 0.8 mg/1, that 
of H approximately 0.9 mg/1.^^ 


Characteristic of 
injury 

Agent 

KB-16 

H 

Latent period for severe injury 

18-36 hr 

6-16 hr 

Conjunctival reaction: 

+ 

+ + + 

Redness 

+ + + 

+ + 

Chemosis 

+ 

+ + + 

Hemorrhagic necrosis 

0 

+ + 

Ischemic necrosis 

0 

+ + + 

Corneal reaction: 

+ + + 

+ + 

Edema 

+ + + 

+ + 

Vascularization 

+ + + + 

+ + 

Ulceration 

+ 

+ + 

Residual opacity 

+ 

+ + 

Purulent discharge 

-f 

+ + 

Iritis 

+ 

+ + 

Relapse 

0? 

+ + 


elusion may be extrapolated to man/'^ it may be con- 
cluded, as with H, that 50 mg min/m^ (^ < 8 hours) 
of KB-16 vapor would be the maximum dosage to 
which unmasked troops could be exposed without 
danger of significant eye damage, and that 200 mg 
min/m^ would suffice to produce totally incapacitat- 
ing eye injuries of several days’ duration. 

In one of the two studies mentioned above the 
eyes of rabbits were exposed to approximately satu- 
rated vapor of KB-16 and of H at 22-24 C for short 
periods, with the results summarized in Tables 5 
and 6.^^^*^ For each exposure time the vapor dosages 
of the two agents were approximately the same, in- 
asmuch as the volatility of H is only slightly greater 
than that of KB-16, but the high vapor concentra- 
tions admittedly represent an artificial situation. In 
the other study dogs were exposed for 10 minutes 
to much lower concentrations of each agent, with the 
results summarized in Table 7. 

Liquid Contamination of the Eye 

As in the case of other vesicant agents, small liquid 
drops (i.e., 0.5 mg or less) of KB-16 produce very 
severe and prolonged injury, frequently leading to 
permanent loss of sight. Like H and in contrast to 
the arsenicals, KB-16 applied in this way does not 
evoke a severe immediate reaction. Discharge and 
edema reach their height on the third day. Lesions 

^ It is known for H and the nitrogen mustards that the 
animal (i.e., rabbit) eye is distinctly less susceptible to injury 
than the human eye. Whether this holds for KB-16 is not 
known. 


Table 7. Effects of the vapors of KB-16 and H on the 
eyes of dogs.i®*" The dogs were exposed for 10 minutes to 
nominal concentrations of the agents in a chamber 
operated at a flow rate of chamber volume per minute. 


Cone. 

Agent 

(mg/1) 

KB-16 

H 

0.01 

No irritation during ex- 

No irritation during ex- 


posure. No eye dam- 

posure. Possible har- 

• 

age developed. 

assment for 1-2 days 
due to very mild cor- 
neal swelling which 
developed within 24 
hours. 

0.02 

No irritation during ex- 

Almost no irritation dur- 


posure. Minor con- 

ing exposure. Possi- 


junctival irritation 

ble harassment for 3 


and corneal edema 

days due to mild cor- 


with increased relu- 

neal and conjunctival 


cency developed with- 
in 1 day and persisted 
for 8-10 days. Negli- 
gible interference with 

symptoms. 


vision. 


0.04 

No irritation during ex- 

Slight irritation during 


posure. Serious inter- 

exposure. Serious in- 


ference with vision 

terference with vision 


for at least 4 weeks 

for 2-3 weeks begin- 


beginning at 2 days. 

ning at 1 day, due 


due chiefly to corneal 

to corneal changes 


damage which became 

(edema, opacity, and 


maximal at 5 days 

ulceration after 1-2 


and subsided very 

days) and inflamma- 


slowly, leaving resid- 

tion of the conjunc- 


ual oj^acity. 

tivas and lids. Maxi- 
mal damage at 4^ 
days. Possibly some 
permanent damage. 


involving the lids appear to be more painful than in 
the case of H, and there is a greater tendency to 
vascularization of the cornea and to iritis but not so 
much tendency to delayed relapses. In comparison 
with HN2, the iritis produced by KB-16 is less vio- 
lent and severe intraocular hemorrhages do not occur. 

Potency of Compounds Related to KB-16 

Preliminary data indicate that N-(/3-chloroethyl)- 
N-nitrosoacetamide is approximately as potent an 
eye-injurant as KB-16 itself,^®f-^^j ethyl N-(jS-chloro- 
ethyl)-N-nitrosocarbamate is 3^-1 times as po- 
tent,^®^’^^bi the corresponding isopropyl ester and 
methyl N-butyl-N-nitrosocarbamate are less than 
one-half as potent, and ethyl N-methyl-N-nitroso- 
carbamate is no more than one-tenth as potent. 

8.4.5 Physiological Mechanism 

The toxicological data summarized above demon- 
strate that the action of KB-16 is confined to a fairly 
severe local necrotizing action on tissues with which 


SECRET 


TOXICOLOGY 


129 


it comes in contact. Practically speaking these tissues 
are those of the eye, respiratory tract, and, when the 
agent is ingested, the gut. In large, intravenously 
administered doses the agent lacks the gross pharma- 
cological actions which characterize H and the nitro- 
gen mustards (Chapter 22). 

The chemical properties which presumably under- 
lie the necrotizing action of KB-16 and the less toxic 
related compounds were reviewed above (Sec- 
tion 8.2.3). In resume two types of reaction have been 
demonstrated to occur with substances of biological 
interest in aqueous solutions at pH 8. First, a gen- 
eral property of N-alkyl-N-nitrosocarbamic acid 
esters is the capacity to transform RNH 2 groups 
into R-NH-CO-OR' groups (carbomethoxylation, 
carbethoxylation, etc.). This reaction characterizes 
not only KB-16 and the corresponding ethyl ester, 
but also nitrosocarbamates (i.e., ethyl N-methyl-N- 
nitrosocarbamate) which do not contain a /S-chloro- 
ethyl group attached to nitrogen. Second, interaction 
of KB-16 or the homologous ethyl ester with a-amino 
acids results in the disappearance of amino groups, 
and, in the case of cysteine, of the sulfhydryl group 
as well. Substances analogous to the “one-armed’’ 
sulfur and nitrogen mustards are presumed to be 
intermediates in these reactions, and conceivably 
may be toxic by virtue of the alkylating power of 
their /3-chloroethyl groups. The /3-chloroethyl group 
of KB-16 itself is relatively unreactive and neither of 
the above-described reactions corresponds to the 
principal mode of interaction of the sulfur and nitro- 
gen mustards with amino, sulfhydryl, and other 
physiologically important groups (Chapter 19). The 
difference in mechanism is further emphasized by the 
fact that KB-16 reacts in nonaqueous media with 
the amino group of benzylamine, whereas reactions 
of the sulfur and nitrogen mustards depend upon a 
preliminary solvolytic activation in water. 

The reaction of KB-16 with hemoglobin in vitro 
supplies a model for povssible reactions of toxicological 
significance, and the absence of a comparably vigor- 
ous reaction with egg albumin suggests that the ef- 
fects of the agent in the cell may be confined to only 
some of the biologically important molecules and re- 
active groups. Biochemical studies do, in fact, reveal 
that some enzyme systems are readily poisoned by 
KB-16, whereas others are not. 

In one study with enzyme systems in vitro, the 
effects of KB-16 were compared with those of 
The three tested systems were inhibited by KB-16, 
but not so effectively as by H ; previously hydrolyzed 


KB-16 was without effect. Purified yeast hexokinase 
was inhibited 60 per cent by 0.006 M KB-16 and 
50 per cent by 0.003 M H. Phosphocreatine phos- 
phokinase was not significantly inhibited by 0.002 M 
and was inhibited 26 per cent by 0.006 M KB-16, 
whereas H at 0.001 M produced an inhibition of 
90 per cent. Inorganic pyrophosphatase was in- 
hibited 70 per cent by 0.001 M H and only 35 per 
cent by 0.002 M KB-16. 

The respiration (oxygen consumption) of slices of 
tissue from a variety of organs was inhibited by 
treatment with 0.001 M KB-16.^® In general the in- 
hibition was greater (even complete) in the absence of 
added oxidizable substrates than in the presence of 
glucose, lactate, pyruvate, or other carbohydrate 
intermediates. The degree of inhibition increased 
with time in some instances. In contrast with its 
effect on oxygen consumption, KB-16 had but a 
slight effect on glycolysis as measured by carbon 
dioxide output or lactic acid production. Some but 
not all aspects of the metabolism of pyruvic acid by 
tissue slices were markedly affected by KB-16. Oxi- 
dation of pyruvate (utilization in presence of oxygen) 
was inhibited, but considerable species and organ 
variation occurred. The dismutation of pyruvate as 
measured by its utilization by chopped brain in the 
absence of oxygen was inhibited to a smaller extent, 
and its decarboxylation by dried yeast was unaf- 
fected. The synthesis of carbohydrate from pyruvate 
by kidney slices (rat) was almost completely in- 
hibited by 0.001 M KB-16, but another condensation 
reaction, the synthesis of acetoacetate from pyruvate 
by chopped pigeon liver, was almost unaffected. Ex- 
periments with rat kidney indicated that the oxi- 
dative deamination of natural amino acids (i.e., 
glutamic) is greatly inhibited by KB-16 but that 
d-amino acid oxidase is unaffected. KB-16 had little 
effect on the oxidation of citrate and fatty acids by 
various preparations. Cholinesterase (Stedman) was 
inhibited by KB-16 but the agent had no significant 
effect on a number of other enzymes including the 
following: carboxylase, succinic dehydrogenase, cyto- 
chrome oxidase, choline oxidase, pepsin, and urease. 

In summary, the primary effects of KB-16 seem to 
be due to the inactivation of certain essential pro- 
teins. Prominent among the sensitive substances 
appear to be the activating proteins of pyruvic oxi- 
dase and Z-amino acid oxidase. Inasmuch as the re- 
actions appear to be irreversible, the combatting of 
injury by KB-16 should be based primarily on pre- 
vention of the reactions. 


SECRET 


130 ALIPHATIC NITROSOCARBAMATES AND RELATED COMPOUNDS 


Table 8. Properties of KB-16, mustard gas (H), and fm(|8-chloroethyl)amine (HNS) bearing upon their utility as 
chemical warfare agents. 

Property 

KB-16 

Agent 

H 

HNS 

Storage stability 

poor 

good 

excellent 

Explosion stability 

questionable 

good 

good 

Factors influencing stability on moist terrain : 




Solubility in water (ppm at room temperature) 

7,000 

500 

80 

Half life in water (min at 25 C) 

? 

8± 

2.4 + 

Volatility (mg/1 at 25 C) 

0.87 

0.96 

0.12 

Freezing point (C) 

<—50 

14.3* 

- 3 



5-9t 


Density (g/ml at 25 C) 

1.21 

1.27 

1.24 

Median detectable cone. (Mg/1) 

7± 

0.6t 

15 + 



1.8* 


Relative eye-injuring potency 

1± 

1 

1 + 

Relative vesicant potency of liquid on not visibly sweating skin < 0.25 

1 

0.25-0.5 

Relative vesicant potency of vapor on sweating skin 

? 

1 

0.6-0.9 


* Pure H. 
t Levinstein H. 


As is the case with H and the nitrogen mustards, 
instillation of very small amounts of KB- 16 into the 
eye results in an inhibition of mitosis in the corneal 
epithelium.^'*'’ This effect is exerted by less than one- 
thousandth of the minimal dose causing clinically 
visible lesions. 

8.5 EVALUATION AS WAR GASES 

KB-16 and the most toxic related compounds (i.e., 
ethyl N-(/3-chloroethyl)-N-nitrosocarbamate and N- 
(/3-chloroethyl)-N-nitrosoacetamide possess insuffi- 
cient storage stability to be seriously considered for 
large-scale manufacture for purposes of chemical 
warfare. It has been suggested that this difficulty 
might be overcome by nitrosating the stable inter- 
mediate, methyl N-(/3-chloroethyl) carbamate, with 
nitrous gases just before use, or by development of a 
munition designed to effect the nitrosation shortly 
before firing or even thereafter. However, comparison 
of the other properties of KB-16 with those of such 
persistent agents as H and HNS (see Table 8) leads 
to the conclusion that KB-16 does not possess suffi- 
cient general utility to merit such special treatment. 
Moreover, in the opinion of the authors, it would not 


deserve serious consideration even if a method for its 
stabilization should be forthcoming. 

KB-16 does possess certain desirable features — 
low freezing point, lack of pronounced odor, and 
effectiveness as an eye-injurant at low dosages. The 
available data do not permit the conclusion that the 
vapor dosages necessary to produce casualties among 
unmasked troops by eye or respiratory injuries would 
be of a different order than the dosages required in 
the cases of H and HNS. Given equivalent low vapor 
dosages, however, KB-16 because of its less pro- 
nounced odor would be a more insidious and there- 
fore more effective agent than H. On the other hand, 
it would not have this advantage over HNS, which 
is less odorous. 

Because of the necessity of assuming that enemy 
troops will be equipped with gas masks, current doc- 
trine gives greater weight to the vesicant effects than 
to the eye-injuring potency or inhalation toxicity of 
a persistent agent not having either much less odor 
or much greater potency (or both) than H, KB-16, 
or HNS. Thus, the relatively low vesicant potency of 
KB-16 places it at a great disadvantage in compari- 
son with H. 


SECRET 


Chapter 9 

FLUOROPHOSPHATES AND OTHER PHOSPHORUS-CONTAINING 

COMPOUNDS 


By Marshall Gates and Birdsey Renshaw 


9.1 INTRODUCTION 

A pproximately 200 phosphorus-containing com- 
pounds of widely varying structures were ex- 
amined as candidate chemical warfare agents during 
World War 11. Only the few represented by the 
dialkyl fluorophosphates, the diamidophosphoryl 
fluorides, the alkyl cyanamidophosphates, and the 
alkyl fluorophosphonates have merited detailed ex- 
amination. The individual compounds that have re- 
ceived most attention are : 


1 . Dialkyl fluorophosphates. 


CH3— O 0 

\ / 
p 

/ \ 

CH3— O F 

Dimethyl fluorophosphate 
(PF-1, TL 311, T-1035) 


CH3CH2— O O 

\ / 

p 

/ \ 

CH3CH2— O F 

Diethyl fluorophosphate 
(TL 345, T-1036) 


CH3 


CH3CH2 


CH3 

CH3 


CH— O CH — 0 

/ \ o / \ o 

' / CH3 \ / 

p p 

CH3CH2 / \ 

\ / F \ / F 

CH— O CH— O 


CH3 CH3 

Diisopropyl fluorophosphate Di-sec-butyl fluorophosphate 
(PF-3, DPF, TL 466, T-1703, (TL 1266, T-1835) 
1152) 


H2C CH2 

/ \ 


H2C CH— O 


\ / 

H2C CH2 

H2C CH2 



/ \ / \ 


H2C CH— O F 


H2C CH2 

Dicyclohexyl fluorophosphate (TL 941, T-1840) 


2 . Diamidophosphoryl fluorides. 
CH3 
\ 

N 

/ \ 0 
CH3 XT’ 

p 

CH3 /\ 

\/ F 

N 


CH3 

6ts(Dimethylamido)phosphoryl fluoride (TL 792, T-2002) 

3 . Alkyl cyanamidophosphates. 

CH3 


N 




0 




P 



\ 

CN 


CH3CH2— O 

Ethyl dimethylamidocyanophosphate 
(MCE, Tabun, Le-100, TL 1578, T-2104) 

4 . A Ikyl fluorophosphonates. 

CH3 


CH— O 0 



H3C 


Isopropyl methanefluorophosphonate 
(MFI, Sarin, T-144, TL 1618, T-2106) 


CH3 


CH— O 0 

/ \ ^ 

CH3 P 

\ 

F 

CH3CH2 

Isopropyl ethanefluorophosphonate 
(TL 1620, T-2109) 


SECRET 


131 


132 


FLUOROPHOSPH AXES AND PHOSPHORUS-CONTAINING COMPOUNDS 


The dialkyl fluorophosphates were described in the 
open literature in 1932. The British undertook their 
examination as war gases in 1941 and much work on 
them was subsequently carried out in the United 
Kingdom and United States. 

They are parasympathetic stimulants and cholin- 
esterase poisons of high potency. For some species 
(e.g., the monkey), PF-3 and di-sec-butyl fluoro- 
phosphate are more toxic than any of the standard 
United States or British chemical warfare agents. At 
lethal concentrations they are “quick-kill” agents, 
their action being only slightly less rapid than that 
of hydrogen cyanide (AC) . However, their relatively 
low volatility, at 25 C 30 mg/1 for PF-1, 8 mg/1 for 
PF-3, and 1.8 mg/1 for di-sec-butyl fluorophosphate, 
puts them in a class with the persistent agents and 
would render difficult the rapid administration of a 
lethal dose under field conditions. Chief interest in 
them has arisen from their action on the eye. They 
produce extreme constriction of the pupil, interfer- 
ence with the muscles of accommodation, potentially 
dangerous congestive iritis, and severe pain behind 
the eyes. PF-3 and di-sec-butyl fluorophosphate at a 
dosage of 50 mg min/m^ produce pupillarv constric- 
tion, and PF-3 at about 300 mg min/m^ produces the 
other harassing symptoms just mentioned. However, 
by 1943 and 1944 careful assessments led to the con- 
clusion that in practice these effects would be harass- 
ing rather than casualty producing. It is believed 
that troops supplied with gas masks would not be- 
come casualties from attack with the fluorophos- 
phates except under circumstances where standard 
nonpersistent agents would have equally or more 
severe consequences. A useful interim summary of 
wmrk on the fluorophosphates was prepared by Di- 
vision 9 in 1944.^^ 

The diamidophosphoryl fluorides proved to be 
about as toxic as the fluorophosphates but to be less 
potent in their action on the eye. Their chief point of 
interest is that they are extremely stable in water and 
upon oral administration are among the most toxic 
of the known synthetic compounds. 

The dialkyl fluorophosphates appear to be eclipsed 
in toxicological potency and potential value as 
chemical warfare agents by the alkyl cyanamido- 
phosphates and alkyl fluorophosphonates. These 
compounds, known collectively as Trilons (a name 
assigned to them by the Germans), first came to the 
attention of United States and British workers after 
the termination of hostilities in Europe in the spring 
of 1945. It was then discovered that the Germans had 


manufactured large quantities of MCE for use in 
bombs and high explosive-chemical shell. They had 
been attempting also to prepare MPT on a large scale 
but had been unable to overcome difficulties in its 
synthesis. 

The Trilons are similar in mode of action to the 
fluorophosphates but are considerably more potent 
both in terms of inhalation toxicity and in the pro- 
duction of eye effects. For the monkey the L{Ct) ^o’s 
of MCE and MFI are in the order of 250 and 150 mg 
min/m^, respectively. In man MCE at the extraor- 
dinarily low dosage of 3.2 mg min/m^ produces 
pupillary constriction. Dosages in the order of 15 to 
20 proved to be definitely harassing because of ocular 
and systemic effects, and it would seem that 30 mg 
min/m^ might suffice to produce significant partial 
disability. Quantitative eye data on MFI are not 
available to the reviewers. Although MCE is some- 
what less volatile than mustard gas (H) and is sus- 
ceptible to hydrolysis, MFI has the rather high 
saturation concentration of 16 mg/1 at 25 C and is 
quite stable. Moreover, it is virtually odorless. 

It would seem that the Trilons are the one new 
group of chemical agents discovered during World 
War II which merit serious consideration for adop- 
tion as standard agents. Their use in high explosive- 
chemical shell, indistinguishable on detonation from 
ordinary high-explosive munitions, should be care- 
fully evaluated and assessment made of the relative 
casualty-producing effects of (1) the initial cloud of 
droplets and vapor and (2) the subsequent vapor 
evolution from the contaminated terrain. 

Division 9 has participated in work on the Trilons 
only to the extent of performing limited studies on 
synthesis, detection, and analysis. Most of the re- 
ports on work done by other agencies have become 
available during the period when the division was 
terminating its activities. Some of these reports may 
not have come to the attention of the reviewers. It 
has not been possible to render the review of the 
Trilons as complete as the discussion of the other 
agents of major importance. A summary of the field 
trials conducted at Raubkammer after the defeat of 
Germany has not been included, and a complete 
assessment of the value of the Trilons as chemical war- 
fare agents has not been undertaken in this chapter. 

9.2 SYNTHESIS AND PROPERTIES 
9.2.1 Synthesis 

Many methods have been used in the synthesis of 
the compounds listed in Table 1. The following dis- 


SECRET 


SYNTHESIS AND PROPERTIES 


133 


Table 1. Fluorophosphates, amidocyanophosphates, fluorophosphonates, and other phosphorus compounds examined as 
candidate chemical warfare agents. 

The compounds are arranged in the following general classes: (1) derivatives of phosphine, (2) derivatives of primary 
phosphines, (3) tertiary phosphines, (4) oxygen, sulfur, and nitrogen derivatives of tricovalent phosphorus, (5) phosphorus 
pentahalides and related compounds, (6) phosphoric and phosphonic acid derivatives and their sulfur analogs, (7) quarter- 
nary phosphonium salts, and (8) miscellaneous compounds. 

The following abbreviations are used: n^, refractive index at ^ C; d\ density in g/ml at < C; specific gravity at 
ti C in reference to water at <2 C; mp, melting point in C; bp^, boiling point in C at p mm Hg; vp^ vapor pressure in 
mm Hg at t C; and voF, saturation concentration (volatility) in mg/1 at t C. 

Centigrade scale is used throughout the table. 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Reference to 
toxicity 
data 

1. 

Phosphorus trifluoride 

10, 106c, 

bp 

101.1° 

106d 

11, 106a 



106d 








mp 

151.5° 

106d 


2. 

Phosphorus monochlorodifluoride 





11 

3. 

Phosphorus dichloromonofluoride 





11 

4. 

Phosphorus tricyanide 

30d 

bpO.6 

150° 

30d 





(sublimes) 




5. 

Phenylphosphine 

27g 




11, 18 

6. 

Ethyldichlorophosphine 

2 

bp760 

94-97° 

2 

11 

7. 

Et hyldicyanophosphine 

27r 

bp^* 

94-96° 

27r 

11, 69d 

8. 

Phenyldichlorophosphine 






9. 

Phenyldicyanophosphine 

27d 


1.1666 

27d 

11, 18 




bp^ 

100° 

27d 





bp2o 

145° 

27d 





mp 

35° 

27d 


10. 

Phenyldithiocyanophosphine 

*27f 




11, 18 

11. 

p-Chlorophenyldichlorophosphine 






12. 

p-T olyldichlorophosphine 






13. 

a-Naphthyldichlorophosphine 






14. 

2-Dibenzofuryldicyanophosphine 

27h 




11 

15. 

3-( N -Ethylcarbazole ) dichlorophosphine 

27h 




11 

16. 

2-Phenoxthiindicyanophosphine 

27h 




11 

17. 

T richloromethy Iphosphine 

27f, 77 




11, 18 

18. 

Triethylphosphine 

27d 

bp7« 

127.5° 

27d 

11 

19. 

Tributylphosphine 

27b 





20. 

Trioctylphosphine 

27d 

bp® 

234-237° 

27d 

11, 18 




mp 

30° 

27d 


21. 

Tridecylphosphine 

27h 




11, 18 

22. 

Diethylphenylphosphine 

27f 




11, 18 

23. 

Diallylphenylphosphine 

27f 





24. 

Dibutylphenylphosphine 

27e 


0.9115 

27e 

11, 18 




bp®** 

185° 

27e 





bpO.® 

116° 

27e 





fp 

25° 

27e 


25. 

<rfs( 2-Furyl)phosphine 

29 




11 

26. 

tris{ 5-tert-Buiy\-2-i uryl )phosphine 


bp® 

175° 

34a 





mp 

97-98° 

34a 


27. 

/3-Chloroethoxydifluorophosphine 





11 

28. 

Phenoxydifluorophosphine 

27n 




11 

29. 

/3-Fluoroethoxydichlorophosph i ne 

30f 




11, 18 




bp®“ 

50° 

30f 





bp760 

140-145° 

30f 


30. 

/3-Chloroethoxydichlorophosphine 

27i 




11, 18 

31. 

/3-Chloroethoxydicyanophosphine 





11, 18 

32. 

2-Methyl-2-nitropropoxydichlorophosphine 





11 

33. 

2-Methyl-2-nitropropoxydicyanophosphine 

27r 




11 




mp 

35-45° 

27r 


34. 

(/3-Chloroethylthio)dichlorophosphine 





11, 18 

35. 

(/3-Chloroethylthio)dichlorophosphine 

27r 


1.5822 

27r 

11 





1.367 

27r 





bpO.8 

127-130° 

27r 



SECRET 


134 FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


Table 

1 {Continued). 




Compound 

Reference 

to 

synthesis 

Physical properties 
Property Reference 

Reference to 
toxicity 
data 

36. (/3,/3'-Dichloroisopropylthio)dichlorophosphine 

27o 


1.5286 

27o 

11 




1.5285 

27o 




bp^ 

70-71° 

27o 


37. Dimethylaminodifluorophosphine 

10 


1.075 

10 

11 



bp 

50° 

10 


38. Diethylaminodifluorophosphine 

27n 




11 

39. Diethylaminodichlorophosphine 

27d 


1.196 

27d 

11 



bp^^ 

72-75° 

27d 




189°/atmos. 

27d 


40. N,N-6is(i8-Chloroethyl)aminodichlorophosphine 

1, 27m 




11 

41 . Ethyl-(|8-chloroethylthio)chlorophosphine 

27p 







bp”-^ 

89-920 

27p 

11, 18 

42 . Diphenyl-/3-chloroethylthiophosphine 

27o 


1.652 

27o 

11, 18 




1.248 

27o 




bp<^ 

148-150° 

27o 




bp2 

158-162° 

27o 


43. Diethoxyfluorophosphine 

105q 

bpi8 

80-81.5° 

105q 

104r 

44. o-Phenylenedioxyfluorophosphine 

27h 




11, 18 

45 . bis( /3-Chloroet hoxy )chlorophosphine 

27i 




11, 18 

46. o-Phenylenedioxychlorophosphine 

27g 




11, 18 

47. 6zs(/3-Chloroethylthio)chlorophosphine 

82 

bp^ 

74-75° 

82 

82 

48. 5is(Dimethylamino)fluorophosphine 

10 


0.975 

10 

11 



bp 

120° 

10 


49 . Ethyl-6ts( /3-fluoroethoxy )phosphine 

35a 

bpO.6 

40-49° 

35a 

11 

50. Phenyldiethoxyphosphine 

27g 




11, 18 

51 . Phenyl-6is(o-chlorophenoxy )phosphine 

27h 




11, 18 

52 . Ethyl-6ts( /3-chloroethy 1 thio )phosphine 

27p 

no®® 

1.5600 

27p 

11, 18 



bp 

115-120° 

27p 


53. Phenyl-6zs(methylthio)phosphine 

27h 




11, 18 

54. Phenyl-5ts(/3-chloroethylthio)phosphine 

55. p-Dimethylaminophenyl-6zs(/3-chloroethylthio)- 

271 




11, 18 

phosphine monoethylate 

27n 




11, IS 

56. Phenyl-6is( /3,/3 '-dichloroisopropylthio )phosphine 

27q 




11 

57. Phenyl-6is(butylthio)phosphine 

27h 




11, 18 

58. Dimethyl hydrogen phosphite 

27h 




11, 18 

59. 5zs(/3-Fluoroethyl) hydrogen phosphite 


bpi-^ 

109-110° 

104p 

104p 

60. Diisopropyl hydrogen phosphite 


bp^^ 

82.5° 

104f 

104f 

6 1 . Trimethoxy phosphine 

27h 




11, 18 

62. Triethoxyphosphine 

27e 


0.968 

27e 

11, 18 



bp^'o 

155-156° 

27e 




bpi4 

36-38° 

27e 


63. <m(/3-Fluoroethoxy)phosphine 

30d 

bpO.6 

100-103° 

30d 

11 

64. <ris(/8-Chloroethoxy)phosphine 

27f 




11, 18 

65. trisi j8-Bromoethoxy )phosphine 

27m 




11, 18 

66. Tributoxyphosphine 

34b 


0.9257 

34b 

11 



bpi2 

124-125° 

34b 


67. <r^s(|8-Chloroethylthio)phosphine 

27j, 82 

bpO.6 

82-83° 

82 

11, 18, 82 

68. <ris(|8-Bromoethylthio)phosphine 

27o 


1.874 

27o 

11, 18 



bp<i 

78-80° 

27o 


69. <ris(Propylthio)phosphine 

70. N,N-6ts(/3-Chloroethyl)amino-6is(/3-chloroethyl- 


bpi6 

173-176° 

104f 

104f 

thio)phosphine 

27m 





71. 5is(Diethylamino)fluoroethoxyphosphine 

30f 

bp25 

108-111° 

30f 

11 

72. <rzs( Piperidino)phosphine 

27h 




11, 18 

73. Phosphorus pentafluoride 

106b 

bp 

- 84.5° 

108 

106b, 106c 



mp 

- 93.7° 

108 


74. Phosphorus pentachloride 





92 

75. Phenylphosphorus tetrafluoride 

27f 




11 

76. Phenylphosphorus dibromodichloride 

27h 




11 

77. Phosphoryl fluoride 

106c 

bp 

- 39.8° 

108 

11, 104j 

78. Phosphoryl chlorodifluoride 





11 

79. Phosphoryl bromodifluoride 





11 


SECRET 


SYNTHESIS AND PROPERTIES 


135 


Table 1 {Continued). 


Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Reference to 
toxicity 
data 

80. Phosphoryl dichlorofluoride 

105c, 105e 

bp 

52-57? 

28c 

11, 106c 

81. Phosphoryl dibromofluoride 





11 

82. Phosphoryl chloride 





92 

83. Chlorocarbonylmethanephosphonylchloride 





11 

84. 2-Chlorohexene-l-phosphonyl chloride 

27j 




11 

85. Diphenylphosphinyl chloride 

27n 




11, 18 

86. Trimethylphosphine oxide 

27i 




11, 18 

87. Triethylphosphine oxide 

27d 

bp 

240° 

27d 

11, 18 



mp 

51° 

27d 


88. Thiophosphoryl fluoride 

106b 

bp 

- 52.3° 

108 




mp 

0 

00 

00 

1 

108 


89. Thiophosphoryl chlorodifluoride 





11 

90. Thiophosphoryl bromodifluoride 





11 

91. Thiophosphoryl dichlorofluoride 





11 

92. Thiophosphoryl dibromofluoride 





11 

93. Thiophosphoryl chloride 





11 

94. Thiophosphoryl bromide 





11 

95. Phenylthiophosphonyl chloride 

27e 


1.376 

27e 

11, 18 



bp'« 

270° 

27e 




bp^3 

144° 

27e 


96. Triphenylphosphine sulfide 





11 

97. Trinaphthylphosphine sulfide 






98. fm(a:-Amylnaphthyl)phosphine sulfide 





11 

99. Triphenylphosphine selenide 





11 

100. Ethyl difluorophosphate 

28e, 105f 


1.25° 

105f 

11, 104g 




85-86°/atmos. 

105f 


101. Phenyl difluorophosphate 


bp*'’ 

95° 

104f 

104f 

102. Ethyl dichlorophosphate 

105f 

bp^* 

71° 

104g 

104g 

103. 2-Methyl-2-nitropropyl dichlorophosphate 





11 

104. N,N-Dimethylamidophosphoryl fluoride 

10 


1.2823 

10 

11 



bp760 

122° 

10 


105. N-Isopropylamidophosphoryl fluoride 

27n 



11 

106. NjN-Diethylamidophosphoryl fluoride 

27n 




11 

107. N,N-6is(/3-Chloroethyl)amidophosphoryl fluoride 

27m 




11, 18 

108. N-Ethylamidophosphoryl chloride 

30b 

bpi5 

122-123° 

30b 

11 

109. N-/3-Cliloroethylamidophosphoryl chloride 

1 10. N,N-j8-Chloroethylmethylamidophosphoryl 

30b 

bpi 

146° 

30b 

11 

chloride 

27j 




11, 18 

111. N,N-Diethylamidophosphoryl chloride 

112. N,N-/3-Chloroethylethylamidophosphoryl 

30b 

bp* 

94.5-96° 

30b 

11 

chloride 

27k 




11, 18 

113. N,N-5is(/3-Chloroethyl)amidophosphoryl chloride 

30a 

mp 

54° 

30a 

11, 18 

114. N,N-Dimethylamidocyanophosphoryl chloride 

25 

bpO.Ol 

53-55° 

25 

69c 



riD 

1.4478 

25 


115. Ethyl difluorothiophosphate 

28e 

bpV60 

78-79° 

‘28e 

11 

116. Ethyl chlorofluorothiophosphate 





11 

117. Ethyl dichlorothiophosphate 

*28e 

bp2'> 

68° 

104g 

11, 18, 104g 

118. N,N-Diethylamidothiophosphoryl chloride 

27d 

d 

1.105 


11, 18 



bp2 

83-86° 

27d 




bpi* 

100° 

27d 


119. Isopropyl ethanechlorophosphonate 

35b 

bp^ 

52° 

35b 

69d 

120. Dimethyl fluorophosphate (PF-1) 

See text 

bp 

145-148° 

28a 

See text 



voP" 

22.9 

12 


121. Methyl ethyl fluorophosphate 

17 

bpi* 

53.8-55.5° 

17 

11, 19 



riD 

1.3643 

17 



. . . 

voP® 

20.7 

69c 


122. Diethyl fluorophosphate 

28e, 105b, 
105c, 

bp760 

169.8 

28d 

See text 


105e 

bp2* 

76-77° 

105f 

. . . 



VOpO 

8.18 

12 


123. /3-Chloroethyl ethyl fluorophosphate 

28i 

bp^ 

70.5° 

28i 

11 



voP'’ 

0.599 

12 



SECRET 


136 


B’LUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


Table 1 {Continued). 


Reference Reference to 

to Physical properties toxicity 


Compound 

synthesis 

Property 

Reference 

data 

124. 6fs(/3-Fluoroethyl) fliiorophosphate 

30e, 105j 

bpi^ 

125-127° 

105j 

104m 



bpO.5 

90-95° 

30e 


125. 6is(i8-Chloroethyl) fliiorophosphate 

28i, 105k 

bp^® 

142-144° 

105k 

11, 18, 104j 



bpO.49 

88-89° 

28i 


126. 6fs(Ethylthio) fliiorophosphate 

105f 

bpi5 

104-107° 

105f 

104g 

127. Diallyl fluorophosphate 





104b, 105a 

128. Dipropyl fluorophosphate 

28h, 105e 

bp2o 

98-100° 

105e 

104b 

129. Diisopropyl fluorophosphate (PF-3) 

See text 


1.3780 

105e 

See text 



bp2® 

84-85° 

105e 




bp760 

183° (est) 

105e 




fp 

- 93° 





vol^" 

5.84 

12 


130. 6is(j8,/3'-Dichloroisopropyl) fluorophosphate 

105k 

bp«-7 

163-165° 

105k 


131. Dibutyl fluorophosphate 

28h 




105a 

132. Di-sec-butyl fluorophosphate 

105f, 1051 

bp”* 

62-64° 

105f 

See text 



vopo 

1.12 

12 


133. Diamyl fluorophosphate 





104b 

134. Diisoamyl fluorophosphate 

105f 

bp2« 

145-148° 

105f 

104b 

135. 6fs(a-Ethylpropyl) fluorophosphate 

105k 

bp2” 

97-98° 

105k 

104j 

136. Dicyclohexyl fluorophosphate 

105i 

riD 

1.4558 

281 

See text 



bpO.3 

116° 

105i 




vol^” 

0.0044 

12 


137. 6is(l,3-Dimethylbutyl) fluorophosphate 

105k 

bp2-7 

102-103° 

105k 

104j 

138. 6is(2-Methylcyclohexyl) fluorophosphate 

105p 

bp«i 

120° 

105p 

105p 



bp0.16 

0 

CO 

105p 


139. 6is(a-Carbethoxyethyl) fluorophosphate 

105k 

bp”” 

126-128° 

105k 

104j 

140. Diphenyl fluorophosphate 

28j, 105f 

bp”.”7 

106-108° 

105f 

104g 

141. 6fs(Triethyllead) fluorophosphate 

105e 

mp 

>200° 

105e 

105e 

142. Diethyl chlorophosphate 

143. bis(/3-Fluoroethyl) chlorophosphate 

30d 

bpO.6 

108-112° 

30d 

11, 18, 104b 

144. Diethyl cyanophosphate 

105r 

bp‘4 

95-97° 

105r 

105r 

145. Diethyl thiocyanophosphate 

105e 

bp*” 

115-125° 

105e 

104d 

146. Ethyl N-phenylamidofluorophosphate 

105n 

mp 

O 

§ 

105n 

105n 

147. Methyl N,N-diethylamidochlorophosphate 

25 

no 

1.4443 

25 

69d 



)3p0.13-0.14 

49-49.2° 

25 


148. Ethyl N,N-dimethylamidocyanophosphate 





(MCE) 

21, 25, 105r 

nn 

1.4243 

25 

See text 




1.077 

25 




bpO.3 

56-58° 

25 




fp 

50.0° 

60 




vor^® 

0.567° 

69c 




voP® 

0.612 

60 


149. Methyl N,N-diethylamidocyanophosphate 

35b 

bp”® 

65-66° 

35b 

69d 

150. Ehhyl N,N-diethylamidocyanopliospliate 

151. Methyl N,N-6fs(j8-chloroethyl)amidocyanophos- 

30c 




69c 

phate 





69d 

152. 6is(Dimethylamido)phosphoryl fluoride 

10, 105m, 105o 

d2® 

1.110° 

10 

See text 



bp*® 

86° 

105m 




bp2 

50° 

10 




vol.2” 

2.16 

12 


153. 6is(Butylamido)phosphoryl fluoride 

105m 

mp 

59.5° 

105m 

104o 

154. 6fs( Diethylamide )phosphoryl fluoride 

105m 


1.4321 

28m 

104o 



bp2® 

83-87° 

28m 




bp-” 

124.5-125.5 

105m 


155. 6fs(Morpholido)phosphoryl fluoride 

105q 

mp 

40° 

105q 

104o 

156. 6fs(Piperidido)phosphoryl fluoride 

105q 

bp”-® 

145° 

105q 


157. 67’s(Anilido)phosphoryl fluoride 

105o 

mp 

143-144° 

105o 

104o 

158. 6fs(Cyclohexylamido)phosphoryl fluoride 

105m 

mp 

127° 

105m 

104o 

159. 5is(Benzylamido)phosphoryl fluoride 

105m 

mp 

96° 

105m 

104o 

160. 6is(MethylaniIido)phosphonyl fluoride 

161. 6rs(Dicyclohexylamido)phosphoryl fluoride 

105m 

bp ”.08 

163-165° 

105m 

104o 


SECRET 


SYNTHESIS AND PROPERTIES 


137 


Table 1 {Continued). 


Reference Reference to 

to Physical properties toxicity 


Compound 

synthesis 


Property 

Reference 

data 

162. 6fs(Dimethylamido)phosphoryl chloride 





104r 

163. Diethyl fluorothiophosphate 

28g 

bpio 

55° 

’28g 

11, 18 

See text 

164. Isopropyl methanefluorophosphonate (MFI) 

See text 

riD^s 

1.3790 

69d 



^25.6 

1.0941° 

69d 




bp'5 

56.5-57° 

25 




Vol25 

16.4 

69e 


165. Isopropyl ethanefluorophosphonate 

22 


1.3872 

22 

See text 



nD^® 

1.3817 

69e 





1.0552 

69e 




bpi* 

67-68° 

22 




vops 

11.6 

69e 


166. 2-Chlorohexene-l-phosphonic acid 

27g 





167. Dimethyl methanephosphonate 

271 




11, 18, 69a 

168. 6is(/3-Chloroethyl) methanephosphonate 

271 




11, 18, 69a 

169. Di-sec-butyl fluoromethanephosphonate 

105k 

bp3 

96-100° 

105k 

104j 

170. Diethyl 2-fluoroethanephosphonate 

105s 

bpi' 

200-202° 

105s 

105s 

171. Diethyl 2-chloroethanephosphonate 

27k 




11 

172. Dimethyl propane-2-phosphonate 

271 




11, 18, 69a 

173. bfs(/3-Chloroethyl) propane-2-phosphonate 

271 




11, 18, 69a 

174. Diethyl a-toluenephosphonate 

105s 

bp*^ 

155° 

105s 


175. Diethyl carbethoxymethanephosphonate 

27e 


1.139 

27e 

11, 18 



bp 

259°(atmos) 

27e 




bp^2 

149-150° 

27e 


176. /3-Chloroethyl diethyl phosphate 


bp** 

144-145° 

104f 

104f 

177. <rfs(/3-Chloroethyl) phosphate 





77 

178. <rfs(/3, jS'-Dichloroisopropyl) phosphate 





77 

179. fris( o-Cresyl) phosphate 





77 

180. <rfs(2-Methyl^-propylphenyl) phosphate 





77 

181. <m(Ethylthio) phosphate 


bp*® 

172-174° 

104f 

104f 

182. Diethyl amidophosphate 


bpo-^ 

131-138° 

104f 

104f 



mp 

45.5° 

104f 


183. Diethyl N-ethylamidophosphate 

30b 

bp®* 

96° 

30b 


184. Diethyl N,N-diethylamidophosphate 

30b 

bp* 

96° 

30b 

11, 18 

185. Dimethyl N,N-5fs(/3-chloroethyl)amidophosphate 





69d 

186. Diethyl N,N-5is(/3-chloroethyl)amidophosphate 

187. 6fs(j8-Chloroethylthio) N,N-6is(/3-chloroethyl)amido- 

30c 

bp*« 

164-165.5° 

30c 

11 

phosphate 

27o 


1.5525 

27o 

11, 18 




1.472° 

27o 




bpO.Ol 

155-160° 

27o 


188. <rfs(Dimethylamido)phosphate 

10 

bp2 

83° 

10 

11 

189. Trimethyl thiophosphate 

27h 




11, 18 

190. Triethyl thiophosphate 


bp2® 

106° 

I04g 

I04g 

191. Phosphonium iodide 

27d 

sublimes 62.5° 

27d 


192. fe<raA:fs( Chloromethyl)phosphonium chloride 

27e 

mp 

192-193° 

27e 

11, 18 

193. /3-Chloroethyltriethylphosphonium iodide 

27g 




11 

194. jS-Bromoethyltriethylphosphonium bromide 

27c 

mp 

235°(d) 

27c 

11, 18 

195. Triethylphenylphosphonium iodide 

27h 




11, 18 

196. Triethyl-p-tolylphosphonium iodide 

27h 




11, 18 

197. Triallylphenylphosphonium bromide 

27g 




11, 18 

198. Triphenylphosphobetaine 

27h 




11, 18 

199. /3-Chloroethyltriphenylphosphonium iodide 

27h 




11 

200. /3-Bromoethyltriphenylphosphonium bromide 

27d 

mp 

268° 

27d 

11, 18 

201. 3-Chloroacetonyltriphenylphosphonium chloride 

27h 




11, 18 

202. j8-Chloroethyl-^rfs(2-furyl)phosphonium iodide 

27i 





203. Ethyl metaphosphate 





104c 

204. Triphenylphosphorusphenylimine 

27h 




11, 18 

205. Phosphonitrilic chloride 





11 


cussion will be limited to methods for the preparation 
of members of those series in which compounds of 
high toxicity are encountered and to methods for the 


synthesis of a few closely related compounds. These 
include the fluorophosphates, fluorophosphonates, 
cyanophosphates, and amidophosphoryl fluorides. 


SECRET 


138 


FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


D I ALKYL FlUOROPHOSPHATES 

Members of this series were first prepared by 
Lange by the action of alkyl iodides on silver flu- 
orophosphate, which in turn had been prepared from 
ammonium fluorophosphate. The overall yield ob- 
tained was poor, approximately 12 per cent in the 
case of diethyl fluorophosphate, “ and the method is 
not suitable for preparations on a large scale. Lange 
observed the characteristic miotic action of the 
dialkyl fluorophosphates. Detailed study of this class 
of compounds was initiated by the British during 
World War IL The class has now been thoroughly 
explored both by British teams and workers of the 
National Defense Research Committee [NDRC]. 
Most of the American synthetic work was carried 
out by NDRC Division 10. 

A number of other methods have been used to pre- 
pare alkyl fluorophosphates. These methods include : 

1. The action of alcohols or phenols on phosphoryl 
dichlorofluoride. 

2. The action of phosphoryl chloride on alcohols 
to give dialkyl chlorophosphates, which are then 
fluorinated with sodium fluoride or hydrogen fluo- 
ride. 

3. Chlorination of dialkyl hydrogen phosphites 
(rarely trialkyl phosphites) to dialkyl chlorophos- 
phates, followed by fluorination as in the preceding 
method. 

The first and third of these methods have found 
the widest application. That based on phosphoryl 
dichlorofluoride appears to be quite general but suf- 
fers from the disadvantage that the fluorination of 
phosphoryl chloride (by antimony trifluoride, cal- 
cium fluoride, or hydrogen fluoride) gives only poor 
yields of the desired dichlorofluoride.^*’"-^®^'''*-”® The 
method has been limited to laboratory preparations. 
The dialkyl hydrogen phosphite method is somewhat 
less general, but in cases where it is applicable excel- 
lent yields are obtained and it is well suited for scal- 
ing up to semi technical production. 

The second method, based on the action of phos- 
phoryl chloride on alcohols, has limited usefulness 
since it has not been possible to obtain satisfactory 
yields in the first step, i.e., in the preparation of 
dialkyl chlorophosphates. 2**' 

Direct esterification of fluorophosphoric acid to 
produce dialkyl fluorophosphates has not been suc- 
cessful.-*’* 

* Improvements on Lange’s preparation of ammonium 
fluorophosphate from ammonium bifluoride and phosphorus 

pentoxide have been reported by Marquina.**® 


Representative examples of preparations illustrat- 
ing these methods are given below. 

1. Phosphoryl dichlorofluoride method — synthesis of dicyclo- 
hexyl fluorophosphate. A mixture of phosphoryl chloride and 
antimony pentafluoride held at 75 C and 190-200 mm Hg is 
treated slowly with antimony trifluoride. The resulting vola- 
tile material is trapped and fractionated to give phosphoryl 
dichlorofluoride, b.p. 52-56 C, in a yield of 34 per cent. The 
procedure given is a modification of that of Booth and Dut- 
ton.**® Yields as high as 33 per cent based on phosphoryl 
Chloride have been obtained using hydrogen fluoride as the 
fluorinating agent.-®*' 

A well-cooled solution of phosphoryl dichlorofluoride in dry 
ether is treated with cyclohexanol. After complete removal of 
hydrogen chloride, the resulting dicyclohexyl fluorophosphate 
is isolated in 50 per cent yield by fractional distillation under 
diminished pressure.*®®* Attempts to prepare this compound 
by the phosphite or the phosphoryl chloride methods have 
been unsuccessful. 2®j 

The follow-^ing compounds have been prepared by this 
method: 

diethyl fluorophosphate *®®** 
dipropyl fluorophosphate *®®® 
diphenyl fluorophosphate *®®* 

6i6-(ethylthio) fluorophosphate *®®* 

6fs(/3-fluoroethyl) fluorophosphate *®®j 
6fs(|8-chloroethyl) fluorophosphate *®®*' 
6is(j8-methylcyclohexyl) fluorophosphate *®®’* 
dicyclohexyl fluorophosphate 28i,io5i 

2. Phosphoryl chloride method — synthesis of dimethyl flu- 
orophosphate {PF-1). Phosphoryl chloride is treated with 
methanol at — 78 C and the mixture is allowed to come to 
room temperature slowly. Hydrogen chloride is evolved rap- 
idly for a period of 2 hours. The mixture is transferred to a 
copper vessel and treated with hydrogen fluoride. Fractiona- 
tion following a crude distillation gives PF-1 in 34.5 to 38.8 
per cent yield.^®® 

The following compounds have been prepared by this 
method; 

dimethyl fluorophosphate 
diethyl fluorophosphate 
diisopropyl fluorophosphate 
6fs(/3-chloroethyl) fluorophosphate ^s* 

A slight modification of the method has been used to pre- 
pare ethyl /3-chloroethyl fluorophosphate and methyl 
ethyl fluorophosphate.*^ By using thiophosphoryl chloride as 
a starting material, derivatives of fluorothiophosphoric acid 
have been prepared, and, by the use of one mole of alcohol 
per mole of phosphoryl or thiophosphoryl chloride in the first 
step, derivatives of difluorophosphoric or difluorothiophos- 
phoric acid. 2®®-*-*®®* 

3. Dialkyl hydrogen phosphite method — synthesis of diiso- 
propyl fluorophosphate (PF-S). A cooled solution of isopropyl 
alcohol in either carbon tetrachloride or ether is treated with 
a solution of phosphorus trichloride in the same solvent and 
then blown with air and treated with ammonia to remove hy- 
drogen chloride. Filtration and fractionation give diisopropyl 
hydrogen phosphite in 82.5-89 per cent yield. This material 
is then chlorinated in 71-80 per cent yield to give diisopropyl 


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SYNTHESIS AND PROPERTIES 


139 


chlorophosphate, which is purified first by blowing to remove 
hydrogen chloride and then by fractional distillation. Fluori- 
nation is accomplished by gentle heating of diisopropyl chloro- 
phosphate in benzene with powdered sodium fluoride. PF-3 
is obtained in 84 per cent yield; the overall yield is thus in the 
order of 60 per cent. Hydrogen fluoride can also be used as a 
fluorinating agent.^®^ Distillation of the intermediates can be 
eliminated and the whole process carried out in the original 
solvent (carbon tetrachloride) without greatly decreasing the 
yield.^'^^' 

The following compounds have been prepared by this 
method: 

dimethyl fluorophosphate 
diethyl fluorophosphate 
diisopropyl fluorophosphate ^.se.iosg 
di-sec-butyl fluorophosphate 
diisoamyl fluorophosphate 
6fs(l,3-dimethylbutyl) fluorophosphate 
6fs(a-carbethoxyethyl) fluorophosphate 
6is(a-ethylpropyl) fluorophosphate 
6fs(/3, /3'-dichloroisopropyl) fluorophosphate 
6fs(/3-fluoroethyl) fluorophosphate ^“1 

The last step of the reaction can be modified so as to replace 
chlorine by groups other than fluorine. Diethylthiocyano- 
phosphate and diethyl amidophosphate have been prepared 
in this way.^**®® 

Semitechnical syntheses of PF-1 and PF-3 have 
been carried out by the dialkyl hydrogen phosphite 
method, but only with the latter compound have 
enough runs been made to standardize conditions. A 
description of the procedures used follows. 

1. Semitechnical preparation of diisopropyl fluorophosphate 
(PF-3).* The main reaction was carried out in a 130-gallon 
Lastiglas-lined jacketed vessel equipped with a lined and 
coated gas inlet pipe, a propeller-type stirrer, a charging pipe, 
sight glasses, manometer connections, and a bottom outlet. 
Steam or refrigerating brine could be circulated through the 
jacket. The reactor was connected to a 10-foot Lastiglas-lined 
steel tower, 6 inches in diameter, which was fitted with a lead 
coil condenser from which distillate could be passed to either 
of two receivers. The bottom outlet of the reactor was con- 
nected to the top of a 40-gallon filter tank equipped for vac- 
uum filtration of the slurry and return of the filtrate either to 
the reactor or one of the receivers. Since plugs developed at 
the bottom outlet in many runs, an additional connection be- 
tween the gas inlet and the top of the filter tank was provided 
to allow transfer of the slurry by this route. All vacuum lines 
led to a 35-gallon separator tank which was connected to a 
three-stage steam ejector. Drain lines leading to a 40-gallon 
lead decontaminating tank were provided. A separate still 
was provided for benzene distillation. 

In a typical run, 212 lb (3.54 pound-moles plus I per cent 
excess) of isopropyl alcohol ( <0.2 per cent water) was cooled 
with brine to — 5 C in the jacketed reactor. Phosphorus tri- 
chloride (160 lb, 1.16 pound-moles) was added gradually with 
cooling and stirring over the course of 4 hours, during which 
the temperature was not allowed to exceed 12 C. The system 
w£is kept under slightly diminished pressure (about 700 mm). 
The mixture was then stirred for 3^ hour before applying 


the full vacuum of the steam jet. Chlorine was passed into the 
reaction mixture at a rate of 12 pounds per hour with contin- 
ued cooling. The end of the reaction (10 hours) was indicated 
by a drop in temperature, even though the rate of flow of 
chlorine was increased. A total of 122 lb of chlorine (1.72 
pound-moles, 48 per cent excess) was used. 

To remove excess chlorine, hydrogen chloride, and iso- 
propyl chloride, the stirred mixture was kept under vacuum 
for 2 hours, during which time the temperature was gradually 
raised to 20 C by passing steam into the jacket of the reactor. 
Ten gallons of benzene was then added and distilled off under 
reduced pressure at a maximum temperature of 30 C. The 
last traces of hydrogen chloride were removed by adding an 
additional 10 gallons of benzene and distilling under reduced 
pressure at reactor temperatures not exceeding 50 C. 

After cooling to 20 C, 19 gallons of benzene recovered from 
a previous run was added. Dry sodium fluoride (95 per cent 
pure, 123.4 lb, 2.8 pound-moles, 142 per cent excess) was in- 
troduced into the reactor through an inlet line by means of a 
funnel. The stirred slurry was heated to reflux during 1 hour 
and held at reflux for 4 hours; it was then cooled and filtered. 
After washing the filter cake with three 5-gallon portions of 
benzene, the filtrate and w^ashings were combined, collected in 
the cleaned reactor, and distilled under reduced pressure. The 
benzene forerun containing about 2 per cent of product w^as 
collected to be used in the following run. One hundred and 
fifty-eight pounds (74 per cent of theory based on phosphorus 
trichloride) of PF-3 w^as obtained. The entire run required 
44 hours. An additional 20 hours was necessary to decontam- 
inate and dry the system in preparation for the next run. 

Preliminary design and round cost estimates for a full-scale 
plant to produce 500,000 lb per month of PF-3 by a batch 
process have been drawm up using data obtained during oper- 
ation of this pilot plant. It is estimated that the capital cost of 
the complete plant would be $700,000. Estimated manufactur- 
ing costs are $0.37 per pound of product, $2,222,000 per man- 
ufacturing year.® 

Round cost estimates for a plant producing PF-3 by a con- 
tinuous process have also been prepared.® Although fewer ex- 
perimental data are available (the estimates are based on 
laboratory scale work only),^ a smaller capital outlay and 
low'er operating costs seem possible. 

A total of 13 kg of PF-3 has been prepared at the British 
Research Establishment at Sutton Oak by a batch process 
resembling that just described. 

2._^ilot plant preparation of dimethyl fluorophosphate 
(PF-1). Three pilot plant runs on a process similar to that al- 
ready described for PF-3 have been carried out to produce a 
total of 35 lb of PF-1. This experience was not sufficient to 
allow standardization of conditions, but it w^as found that the 
temperatures required, w'hich are somewhat low^er than those 
^ in the PF-3 process, could be maintained w ithout difficulty. 
Because of mechanical difficulties, yields approaching those 
obtained in the laboratory (72 per cent) w^ere not realized in 
these three runs.** 

Diamidophosphoryl Fluorides 

A number of compounds in this series have been 
prepared by the application of the following more or 
less straightforward methods. 


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140 


FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


1. The action of amines on phosphoryl dichloro- 
fluoride. 

2. The controlled action of amines on phosphoryl 
chloride followed by fluorination . 

3. The action of amines on phosphoryl fluoride. 

The first of these methods appears to be general. 

It is carried out by adding a solution of phosphoryl 
dichlorofluoride in ether, benzene, or toluene to four 
moles of the amine in the same solvent. After filtra- 
tion from the precipitated amine hydrochloride, the 
product is isolated by distillation or crystallization. 
The following compounds have been prepared in this 
way: 

dianilidophosphoryl fluoride 

(dime thy lamido) phosphoryl fluoride io,io5m 

6is(diethylamido) phosphoryl fluoride 28g,io5m 

6ts(butylamido) phosphoryl fluoride 

6is(cyclohexylamido) phosphoryl fluoride 
(me thy lanilido) phosphoryl fluoride 

6is(benzylamido) phosphoryl fluoride 

A modification of this method involving prior 
treatment of phosphoryl dichlorofluoride with one 
mole of alcohol has yielded ethyl N-phenylamido- 
fluorophosphate.^®^*" 

The second method also appears to be general, and 
avoids the use of the difficultly available phosphoryl 
dichlorofluoride. The fluorination of 6is(alkylamido)- 
phosphoryl chlorides proceeds somewhat less readily 
than that of dialkyl chlorophosphates. The method 
has been used successfully with 6^s(ani lido) phos- 
phoryl fluoride and with (dime thy lamido) phos- 
phoryl fluoride. 

The third method suffers from the disadvantage 
that a large part of the fluorine is wasted. It has been 
used to prepare 6zs(dimethylamido) phosphoryl flu- 
oride.^® 

Alkyl Cyanoamidophosphates 

Although vague but persistent rumors of a new 
German gas, Trilon, reached Allied hands from time 
to time during World War II through intelligence 
channels, no reliable information as to the nature of 
this gas or gases became available to the Allies until 
the spring of the German surrender, when German 
munitions charged with a new agent were captured. 
The agent was very quickly identified as ethyl di- 
me thylamidocyanophosphate (MCE) and an in- 
tensive study of it covering all phases of interest to 
chemical warfare was started. About the same time 
an intelligence team interviewing members of the 
staff of the I. G. Werke, Elberfeld, reported that this 


compound had been discovered in 1937 by I. G. 
Elberfeld during a search for new insecticides, and 
that in the following year an even more toxic and in- 
sidious substance, isopropyl methanefluorophospho- 
nate, had been discovered. Both compounds had 
been reported to the War Ministry under its standing 
order to the German chemical industry regarding the 
reporting of toxic substances. 

The laboratory method of synthesis of ethyl di- 
methylamidocyanophosphate (MCE), disclosed in 
detail by the I. G. representatives, made use of the 
following steps. 

1. The interaction of two moles of dimethylamine 
and one of phosphorus oxychloride, first at 30 C and 
finally at 120 C, to produce dimethylamidophos- 
phoryl chloride in 95 per cent yield. 

2. The action of sodium cyanide and ethanol on 
dimethylamidophosphoryl chloride to give MCE in 
90 per cent yield. 

This procedure has been checked in at least two 
laboratories in this country and the German 
claims substantially confirmed, although the yields 
obtained were not so high. No detailed study of the 
reactions was carried out. A novel alternative method 
for laboratory preparation of the agent has been 
used in Great Britain. In this procedure, diethoxy- 
phosphorus chloride is allowed to react with 
dimethylamine and the resulting diethoxydimethyl- 
aminophosphorus is treated with cyanogen iodide to 
give MCE directly. 

In 1939-40 the Germans began pilot plant produc- 
tion of MCE at Munsterlager, near Bremen, and ex- 
perienced no difficulty in the manufacture of 50 tons 
of the material. Construction of a large plant at 
Dyhernfurth near Breslau was begun in January 
1940, but production did not begin until April 
1942. '^2, 73 plant process, chlorobenzene was 

used as a reaction medium in the final step. Initially 
the product was stripped to a content of approxi- 
mately 5 per cent of chlorobenzene. Later a product 
containing 20 per cent chlorobenzene was standard- 
ized. Both 105-mm shells and 250-kg bombs were 
charged with the agent. A total of 10,000 to 12,000 
tons of MCE was produced. It is worth noting 
that the figure 12,000 tons represents 18 per cent of 
the total German production of war gases of all 
kinds, which gives some indication of how largely 
this agent figured in the plans of the Germans. 

MCE is a high-boiling, fairly stable liquid pos- 
sessing a faint fruity odor. The pure material is color- 
less, but as technically produced MCE is dark browm. 


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SYNTHESIS AND PROPERTIES 


141 


It boils at 83 C under 1.5-mm pressure, at 120 C 
under 10-mm pressure, and at 230 C with some de- 
composition at atmospheric pressure. Its density 
at 20 C is 1.077 and its refractive index (n^p) is 
1.4240.®® Its vapor pressure appears to be about one- 
half that of H and can be represented as a function 
of temperature by the following equation:®® 

logioP(mm) = 11.345 - • 

Its volatility at 25 C is 0.567 mg/l.®®‘' The tactical 
use of the agent as an aerosol produced by heavy- 
walled shell equipped with large bursting charges 
appears to have been envisaged by the Germans. 

MCE is claimed by the Germans to be the opti- 
mum compound of this series as regards toxicological 
properties,^® but this assertion has not been verified 
in this country since no comprehensive synthetic 
program was established to explore the field. 

A related compound of relatively high toxicity was 
encountered during an attempt to prepare the iso- 
propyl analog of MCE by the simultaneous action 
of sodium cyanide and isopropyl alcohol on dimethyl- 
amidophosphoryl chloride. In this case the cyano 
group alone was introduced, and dime thy lamido- 
cyanophosphoryl chloride was obtained in 68 per 
cent yield. Its toxicity is approximately one-half 
that of MCE.2® 

Alkyl Fluorophosphonates 

Mention has been made of the discoveiy of this 
class in 1938 by members of the staff of I. G. Elber- 
feld. The optimum compound of the series, isopropyl 
methanefluorophosphonate (MFI), is several times 
as toxic for most species as is MCE, is more volatile, 
and is also more difficult to detect by odor. It aroused 
great interest among the German's, but in spite of 
intensive efforts to develop manufacturing methods, 
production on a plant scale was never realized. 

As first reported to intelligence teams, the labora- 
tory preparation of MFI proceeded as follows. 

Dimethyl hydrogen phosphite is prepared in 90 per 
cent yield by the action of methanol on phosphorus 
trichloride, and is converted into dimethyl methane- 
phosphonate in 85 per cent yield by the action of 
metallic sodium followed by methyl chloride. Finally, 
methanephosphoryl chloride, produced by the action 
of phosphorus pentachloride on dimethyl methane- 
phosphonate, is converted to MFI by the simultane- 
ous action of sodium fluoride and isopropyl alcohol. 
The yields in these steps are 90 and 82 per cent re- 
spectively. 


Attempts by both American and British groups to 
use this scheme without modification were not en- 
tirely successful. In this country yields greater than 
14 per cent were not obtained in the methylation step 
even when methyl iodide was substituted for methyl 
chloride or when the reaction was carried out in an 
autoclave at 125 C. By using dimethyl sulfate, how- 
ever, yields of 77 per cent were obtained in this step.^® 
British workers were able to carry out the methyla- 
tion step in 59 per cent yield by using a modification 
of the original German procedure in which dimethyl- 
hydrogen phosphite was alkylated by treatment with 
sodium sand in dry ether followed by methyl chlo- 
ride.^®®® Neither group obtained greater than 42 per 
cent in the final fluorination and esterification. 

After this work was well under way, additional in- 
formation became available from intelligence sources 
to the effect that the Germans had used sodium 
methoxide in methanol instead of metallic sodium in 
the methylation step and that two alternative 
methods for the final fluorination, one using sodium 
fluoride and the other hydrogen fluoride, were pos- 
sible. The use of hydrogen fluoride made possible 
operation at lower temperatures but introduced cor- 
rosion problems. Few details on the actual operation 
of the final step are available.'^® 

The substitution of higher alcohols for methanol 
in the first step of this process appears to be advan- 
tageous. Dimethyl hydrogen phosphite is rather 
unstable, is water-soluble, and its sodium salt is in- 
soluble in organic solvents. Diethyl hydrogen phos- 
phite has given better results in the hands of British 
workers, particularly in the methylation step,^®’^®®® 
whereas the use of butanol to give dibutyl hydrogen 
phosphite followed by methylation with dimethyl 
sulfate and sodium methoxide was adopted as opti- 
mum for a simplified process suitable for pilot plant 
use by NDRC workers.^'^ In the latter example, the 
solubility of sodium dibutyl phosphite in organic 
solvents appears to be distinctly advantageous. By 
this method methanephosphoryl chloride can be 
obtained in 79 per cent overall yield. Other improve- 
ments made during this study were substitution of a 
water-wash for filtration to remove sulfate salts after 
the methylation, and combination of the first three 
steps to eliminate all distillations except that of 
methanephosphonyl chloride. 

The isomerization process of Arbusow “® has also 
been used to prepare dialkyl methanephosphonates. 
Dimethyl methanephosphonate is obtained in 95 per 
cent yield by heating trimethyl phosphite with 


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142 


FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


methyl iodide/®^® whereas a similar reaction using 
tributyl phosphite yields 89 per cent of dibutyl 
methanephosphonate.^^ 

A novel process well suited for conversion to plant 
scale operations has been developed on a laboratory 
scale for the synthesis of the ethyl analog of MFL 
In this process tetraethyllead is allowed to react un- 
der nitrogen with phosphorus trichloride to give 89 
to 96 per cent of the theoretical yield of ethylphos- 
phorus dichloride, which is then converted in 85 to 
95 per cent yield to ethanephosphoryl chloride by the 
action of sulfuryl chloride. Treatment with sodium 
fluoride and isopropyl alcohol converts this substance 
into isopropyl ethanefluorophosphonate in 72 to 
85 per cent yield. The first two steps can be carried 
out in the same vessel.^^ The resulting ethyl analog 
of MFI has about three-fourths the toxicity of MFI 
itself. No attempt has been made to synthesize MFI 
by a similar process using tetramethyllead, which is 
reputed to be much less easily handled than tetra- 
ethyllead. 

Pilot plant production of MFI has not been under- 
taken in this country. The efforts of the Germans to 
produce this substance on a plant scale were not suc- 
cessful. Although intermediates for the material were 
made in substantial quantity (300 tons of dimethyl 
hydrogen phosphite, 5 to 10 tons of dimethyl meth- 
anephosphonate, and 1 to 2 tons of methanephos- 
phoryl chloride were produced), not more than 3^ ton 
of MFI itself was produced. Corrosion appeared 
to have been the principal source of difficulty. Equip- 
ment shortages necessitated the use of resin-coated 
equipment where stainless-steel or glass-lined equip- 
ment would ordinarily have been used. Silver-lined 
equipment was resorted to in some cases. 

MFI is a colorless, almost odorless liquid boiling 
at 59 C at 8 mm of mercury. Its volatility at 25 C is 
16.4 mg/1.®^ It is less stable than MCE, but can be 
stabilized by the addition of 0.5 per cent of diethyl- 
amine. 

9.2.2 Chemical Reactions, Detection, 
and Analysis 

Studies on the chemistry, detection, and analysis 
of phosphorus compounds as candidate chemical war- 
fare agents have been limited almosP exclusively to 
PF-3, certain of its close relatives, and MCE. 

Dialkyl Fluorophosphates 

Solutions of PF-1 in 0.9 per cent saline lose virtu- 
ally all toxicity in 3 hours. This deterioration is re- 


tarded by buffering the solutions near neutrality but 
is markedly accelerated by buffering at pH 9.7.2®« 
PF-3 is hydrolyzed slowly at room temperature by 
water to give fluoride ion and diisopropyl phosphoric 
acid. This hydrolysis is less than 50 per cent com- 
plete in 15 hours and is still incomplete after 23 
hours. ^ In neutral aqueous solutions at body temper- 
ature the half-hydrolysis time is about 9 hours.®® In 
2 per cent aqueous alkali PF-3 is rapidly hydrolyzed 
at room temperatures, although more concentrated 
alkalies appear to retard this hydrolysis.^®®® his{Di- 
methylamido)phosphoryl fluoride appears to be con- 
siderably more stable to hydrolysis than PF-3.®® 

In contrast to the ease with which fluoride ion is 
freed by aqueous alkalies, the isopropyl groups of 
PF-3 are very resistant to alkaline hydrolysis. For 
example, no isoprop34 alcohol can be detected after 
refluxing with 10 per cent sodium hydroxide for 
72 hours.®^^ Advantage is taken of this resistance to 
hydrolysis in several of the analytical procedures for 
PF-3 based on determination of fluoride ion, the 
titration of which is interfered with by phosphate ion 
but not by alkyl phosphates.’’®-^®®* 

The kinetics of hydrolysis of PF-3 have been stud- 
ied in several laboratories.*®-®**’’®® In addition to the 
marked catalysis by alkali already noted, the reaction 
is also acid-catalyzed, and thus in pure water is auto- 
catalytic. In buffered solutions the hydrolysis is 
pseudomonomolecular. The observation of a pro- 
nounced acceleration by phosphate ion suggests that 
the decomposition may be subject to general base 
catalysis as well as acid catalysis, although acetate 
ion is the only other anion which has been observed 
to have an accelerating effect.^® 

When hydrolysis of PF-3 is allowed to proceed in 
acid solutions, the course of the reaction may become 
complex. For example, in some experiments, acetone 
and isopropylphosphorous acid were formed in addi- 
tion to fluoride ion, and no phosphate ion could be 
detected. Other dibasic acids were likewise absent. 
Acetone is also formed when acid solutions of diiso- 
propylphosphoric acid are treated with sodium flu- 
oride. It has not always been possible to reproduce 
these experiments, however, and the mechanism by 
which acetone and isopropylphosphorous acid are 
formed is not yet clearly understood.^® 

PF-3 does not react with sodium hypoiodite to give 
iodoform and does not react with thiosulfate ion.®**’-® 
Methods for the detection and analysis of com- 
pounds of the fluorophosphates series are summa- 
rized in Chapters 34 and 37. The following general 


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SYNTHESIS AND PROPERTIES 


143 


remarks may be supplemented by reference to these 
chapters. 

The fluorine atom of PF-3 and related compounds 
is readily converted to fluoride ion on hydrolysis and 
any detection methods depending upon the recog- 
nition of fluorine ion are thus applicable to these com- 
pounds. The ability of fluoride ion to bleach metallic 
lakes of certain dyes or its etching effect on glass has 
been utilized for recognition. 

A device making use of the etching effect has been 
examined by the British. 

The decomposition of volatile fluorine compounds 
by hot platinum filaments or hot platinized silica gel 
to produce hydrogen fluoride is applicable to mem- 
bers of the fluorophosphate series. 

Detection of PF-3 collected upon plain silica gel 
tubes can be accomplished by testing either for 
fluoride ion or for phosphate ion after suitable treat- 
ment. The DB-3 reagent may also be used.^^ 

Chemical methods for the detection of fluorine 
compounds, including PF-3, in water have been de- 
veloped.'‘^-'‘2 Use of the miosis produced by PF-3 as a 
method for detection of this agent in water has also 
been proposed. It is claimed that 25 to 50 ppm can 
be detected in 3 minutes by this method without 
injury to the eye.'^® 

The analysis of PF-3 has been accomplished by 
volumetric, colorimetric, or gravimetric determina- 
tion of the fluoride ion produced by alkaline hydroly- 
sis. Alternately, phosphate ion can be determined 
colorimetrically after vigorous acid hydrolysis with 
hydrobromic, hydriodic, or sulfuric acids. 

105e,t,106f 

Methods suitable for use in field and chamber 
analyses of PF-3 have been described. 

Ethyl Dimethylamidocyanophosphate (MCE) 

MCE is readily destroyed in either acidic or basic 
solutions.®^ ’“2 In alkaline solutions, cyanide ion is 
liberated rapidly even in the cold, the half life at 25 C 
being 5 minutes at pH 8.5 and 30 minutes at pH 
7.5.®^ In acid solutions rapid liberation of dimethyl- 
amine occurs, the half life in solutions of pH 1 being 
2 minutes, that in solutions of pH 3, 90 minutes. The 
substance has maximum stability at pH 4.5, where 
its half life is 7 hours with respect to both cyanide 
ion formation and dimethylamine liberation. Solu- 
tions of maximum stability result from hydrolysis in 
unbuffered solutions, since the hydrolysis products 
are acidic and self-buffering in the range pH 4 to 5.®^ 

In solutions of high acidity (i.e., 3 normal), hydro- 


gen cyanide as well as dimethylamine is liberated 
rapidly but complete degradation to phosphoric acid 
results only from boiling the substance with mineral 
acids. 

Bleach and chlorinating agents react readily with 
MCE to yield 

MCE is extremely hygroscopic, and moist solu- 
tions of it slowly liberate AC.®^ ®®^ Its faint fruity 
odor cannot be relied on for detection. Its median 
detectable concentration as determined with the 
osmoscope is 2.2 ;ug/l.®®^ 

The standard liquid vesicant detectors, both Brit- 
ish and American, give positive reactions with MCE. 
This is true of the H papers of the kit, food testing, 
and of the M-6 paper, M-7 crayon, and M-5 detector 
paint of the United States Chemical Warfare Service, 
and of the British Detector, Gas, Ground. The Brit- 
ish differential detector powder gives a yellow color 
with the agent.®®^’^®’^^2 The black dot (AC) tube of 
the M-9 detector kit has about the same sensitivity 
for MCE vapor as it has for AC itself (20 ^g) but is 
considerably less sensitive than the German AC tube 
(sensitivity 2-3 Mg)- The red dot (nitrogen mustard) 
tube gives a nonspecific test.”^® The British pocket 
vapor detector gives no reaction with the agent. 
The ready production of cyanide ion and a volatile 
amine on alkaline and acid hydrolysis, respectively, 
together with the production of phosphate ion on 
ultimate hydrolysis, can be taken as confirmatory 
identification. 

For field or chamber analysis, MCE can be col- 
lected in 1.25 normal sodium hydroxide and titrated 
with silver nitrate,^®'®^-®®® or (for small amounts) esti- 
mated colorimetrically with sodium picrate.^®’®®^’®®^ 
Phosphorus colorimetry using molybdivanadophos- 
phate is also suitable if the sample, collected in al- 
kali, is fumed with perchloric acid or otherwise 
completely decomposed. The sensitivity of this 
method is several times as great as that of those 
already described.^® ®^ Attempts to adapt the DB-3 
method to the analysis of MCE have not been en- 
tirely successful.®®*" 

9.2.3 Stability 

Dialkyl Fluorophosphates 

PF-3 is stable when stored in glass at 25 C. When 
stored in steel at 65 C, slight decomposition takes 
place as indicated by sludge formation. This decom- 
position continues at an increased rate when the 
sample is removed and stored in glass at 25 C. This 


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144 


FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


effect may be due to the action of light and dissolved 
iron salts. 

In the presence of steel at 58-60 C, diethyl fliioro- 
phosphate appears to stable for several months.^*^ 
Both PF-1 and PF-3 are resistant to flashing. No 
temperature has been found at which dimethyl flu- 
orophosphate flashes; PF-3 can be made to flash 
feebly over a narrow temperature range. 

Ethyl Dimethylamidocyanophosphate (MCE) 
Technical MCE containing 20 per cent mono- 
chlorobenzene is reported by the Germans to be 
stable even on prolonged storage. 

It is also claimed by them that MFI, when stabi- 
lized with < 1 per cent of diethylamine, can be stored 
in iron and that it is stable in methanol solution. It 
was supposed to have been used in such solutions. 

9.2.4 Decontamination 

Dialkyl Fluorophosphates 

Bleach suspensions and dry bleach react vigor- 
ously with PF-3 and presumably with other fluoro- 
phosphates, and normal field decontamination pro- 
cedures as used for vesicants should be effective. The 
chloramides S-461 and S-328 do not react with 
PF-3 or dieth 3 d fluorophosphate, nor do dilute solu- 
tions of calcium hypochlorite. 

The ease of hydrolysis of the fluorine atom of the 
dialkyl fluorophosphates by water alone varies con- 
siderably with structure. PF-1 is 72 per cent hy- 
drolyzed after standing 1 hour in water at 24 C; the 
diethyl compound, 24 per cent; and the PF-3, 1 per 
cent. However, dilute alkalies at room temperature 
produce rapid hydrolysis of all three esters.^ Lime 
slurry should thus be an effective decontaminant. 
Dilute solutions (approximately 0.4 per cent) of 
sodium hydroxide have been proposed for skin de- 
contamination . 

Mere hosing of contaminated areas with water 
should mitigate the vapor hazard produced by PF-3, 
since it is soluble to the extent of 1.5 per cent in 
water. 

Ethyl Dimethylamidocyanophosphate (MCE) 

In the Dyhernfurth plant of the Germans, equip- 
ment used for the synthesis of MCE was decontam- 
inated by steam and ammonia. Surface decon- 
tamination, in the absence of steam, was done by 
solutions of ammonia or of amines. 

Alkalies or bleach and water have been recom- 
mended by the Chemical Warfare Service for decon- 
tamination, but it is recognized that the production 


of CK by the action of bleach on MCE might prove 
hazardous under some conditions.'^® 

9.2.5 Protection 

Dialkyl Fluorophosphates 

Adequate protection against dialkyl fluorophos- 
phates appears to be provided by United States, 
British, German, and Japanese canisters, and it is 
doubtful whether canister penetration by these 
agents will ever be a significant problem. Repre- 
sentative United States, German, and Japanese 
canisters have been tested against PF-1, PF-3, and 
methyl ethyl fluorophosphate; all afforded good pro- 
tection.^^ The standard United States Navy can- 
ister provides complete protection against PF-3 as 
does the British Lt. Mk. II canister.'^^-^^ 

Ethyl Dimethylamidocyanophosphate (MCE) 

Completely adequate protection against the vapor 
of MCE is afforded by American, British, and German 
canisters 62,70,72,90,112 jg implied in intelligence 

reports that the German canister gives adequate 
protection against MFI.^^ American canisters 
(M-11 and M-lOA-1) give adequate protection 
against ethyl dimethylamidocyanophosphate as an 
aerosol (particle size 2 /z, concentration 100 Mg/1, 
flow rate 32 1pm), but the Canadian canister, which 
has a resin wool pad-type filter, allows serious pene- 
tration after 5 minutes."^® It is to be noted that the 
tactical use of the agent contemplated by the Ger- 
mans was as an aerosol. 

Combined activated carbon-aeration treatment of 
water contaminated with MCE gives excellent re- 
moval of cyanide ion, odor, and color but does not 
remove organic phosphorus if the water has been 
standing more than 15 hours after contamination. 

9.3 TOXICOLOGY 

9.3.1 Detectability by Odor and Other 
Physiological Signs 

The Trilons and fluorophosphates may be detected 
by (1) odor, (2) a feeling of tightness in the chest 
and/or throat, and (3) pupillary constriction. 

MCE and PF-3 have faint, sweetish odors. The 
available osmoscopic data for these and other agents 
are presented in Table 2. It is apparent that the 
fluorophosphates are relatively odorless. Crude 
MCE (German shell filling) is more readily detected 
but does not possess so pronounced an odor as H. 
MFI is said to be odorless, or practically so.^®^* 


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TOXICOLOGY 


145 


Table 2. Detectability by odor of MCE, fluorophos- 
phates, and other representative agents as determined by 
the osmoscopic technique. 


Agent 

Median 
detectable 
cone. (Mg/1) 

Reference 

MCE (German shell filling) 

2.2 

66h 

PF-3 

36 

49 

Dimethyl fluorophosphate 

18 

49 

Diethyl fluorophosphate 

15 

49 

H (plant run Levinstein) 

0.6 

51 

H (pure thiodiglycol) 

1.8 

65 

HNS (plant run) 

15 

66m 

AC 

34 

39 

CG 

4.4 

38 


In man-chamber experiments a German shell fill- 
ing containing MCE with 20 per cent monochloro- 
benzene was detected at a concentration of 1.6 Mg/l 
by 2 of 10 subjects.®* The pure agent seemed to be 
more odorous and was detected at a concentration 
of 0.35 /xg/1 by each of 4 subjects.*® It is possible that 
the Germans considered decreased detectability by 
odor to be one advantage of the addition of mono- 
chlorobenzene to MCE. In one of the man-chamber 
experiments with PF-3, concentrations of 37 to 70 
/xg/1 remained undetected by odor.“ In a field (an- 
nulus) test PF-3 could be detected at an average 
concentration of 0.5 ^ug/l but the odor was not suffi- 
ciently characteristic to be easily identifiable. 

Man-chamber experiments indicate that throat 
irritation and a feeling of tightness in the chest are 
apparently more sensitive indicators of exposure to 
MCE and PF-3 than are the odors. In the case of 
MCE, 6 of 10 observers exposed to the German shell 
filling at a concentration of 1.6 ^tg/l experienced the 
feeling of chest constriction, as did each of the 4 who 
were exposed to 0.35 /xg/l of pure MCE.** In the case 
of PF-3 each of 18 subjects exposed to 8.2 fig/\ — 
not detected by odor — experienced throat irritation 
and a feeling of chest constriction within 60 to 90 
seconds.^® 

Pupillary constriction to pin-point size develops 
within a matter of minutes upon exposure to mod- 
erate dosages of MCE and PF-3, although it is longer 
delayed at the minimal effective concentrations (see 
the following paragraph). 

The foregoing suggests that troops having masks 
available could protect themselves against danger- 
ous dosages of MCE and PF-3 if they could take 
note of odor, feeling of chest constriction, and pupil- 
lary size. High concentrations could be detected 
quickly by odor or chest and throat signs, and the 


mask donned before a large dosage had reached the 
eyes or lungs. Sufficiently low concentrations to 
escape these means of detection would be revealed 
after some minutes or an hour by pupillary constric- 
tion, and the mask applied if more prolonged ex- 
posure were unavoidable. Thus, except upon very 
sudden exposure to high concentrations of vapor and 
aerosol, dosages sufficient to produce systemic ef- 
fects would seem to be theoretically avoidable. It is 
much more difficult to detect exposures to small 
dosages sufficient to produce miosis and the other 
harassing but not disabling symptoms described in 
Section 9.3.2, and it is in this sense that MCE and 
PF-3 may be considered insidious. Accidental ex- 
posures to undetected dosages that resulted in these 
symptoms are reviewed in the next section. It has 
been emphasized that PF-3 is readily absorbed by 
lacquer, rubber, clothing, and hair. The gradual de- 
sorption of vapor can result in obtaining, within con- 
fined spaces, concentrations which suffice to produce 
eye effects but which may remain undetected until 
these effects appear.*^ 

The lack of odor of MFI may not prove to be so 
great an advantage as would appear at first sight if 
throat irritation and feeling of chest constriction 
should prove to be definite indications of the inhala- 
tion of very low concentrations. 

9.3.2 Eye Effects 

The vapors of the fluorophosphates and Trilons 
are absorbed directly by the eye and produce con- 
traction of the pupil (miosis) and interference with 
the muscles of accommodation. As a consequence 
harassment due to poor dim light vision in dim light 
and to pain and difficulty of focusing is experienced. A 
potentially dangerous congestive iritis can develop 
and pain behind the eyeball frequently becomes very 
severe. These ocular symptoms can be relieved by 
(repeated) instillations of a mydriatic (e.g., atropine) 
but the subject is left with a dilated pupil and para- 
lyzed accommodation. The concomitant systemic 
effects often include a feeling of tightness in the chest, 
nausea, and vomiting. No data are available concern- 
ing the exposure of human subjects to dosages suffi- 
ciently large to produce more severe disability. 

Studies on Animals 

Tests of the effects of dialkyl fluorophosphates on 
the eyes of animals originally served (1) to demon- 
strate beyond reasonable doubt that cautious trials 
with human volunteers (see the next section) could 


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FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


be carried out without risk of causing permanent eye 
damage, and (2) to determine the relative miotic 
potencies of some of the compounds. 

Various observations have demonstrated that 
pupillary constriction is produced in rabbits and mon- 
keys at dosages considerably smaller than those re- 
quired to cause permanent ocular injury or marked 
systemic The factor of 

safety in the case of PF-3 is most strikingly illus- 
trated by experiments with rabbits. Instillation into 
the conjunctival sac of a nearly lethal dose of the 
liquid (i.e., 1.15 mg/kg) and repeated instillations of 
smaller doses, while eliciting intense miosis, lacrima- 
tion, and a transient increase of intraocular pressure, 
caused no permanent ocular injury. Similarly, al- 
though vapor dosages of less than 1,000 mg min/m^ 
sufficed to induce marked pupillary constriction, 
dosages of 15,000 mg min/m^ caused no permanent 
damage.®^^'^®^^ In the case of both PF-1 and PF-3 
the vapor dosages necessary to produce miosis in the 
rabbit are considerably smaller than those required 
to kill.^®^® With the monkey, a species that is excep- 
tionally sensitive to the lethal actions of PF-3 and 
di-scc-butyl fluorophosphate, the difference between 
dosages producing miosis and serious systemic poi- 
soning may be smaller,^®'" ^-'!’^’®^-®'^ as may also be the 
case with man (see next section). 

Tests with rabbits have demonstrated that PF-3 
is a markedly more potent pupillary constrictor than 
are the dimethyl, diethyl, dipropyl, or diallyl es- 
ters.‘*9.io4b Qjjiy produces constriction at lower 

dosages, but also for longer times.^^’^®-^®^*^ Illustrative 
data are presented in Table 3. 

Table 3. Relative miotic effects of several dialkyl fluoro- 
phosphates in rabbits.^®^*^ 

The animals were exposed for 3 minutes to nominal con- 
centrations of 1/50,000 (0.11 to 0.16 mg/1). 

Average per cent of initial 
Dialkyl ester of pupil diameter 

fluorophosphoric After After After 

acid 10 min 100 min 300 min 


Dimethyl (PF-1) 

32 

82 

100 

Diethyl 

27 

58 

85 

Dipropyl 

45 

68 

96 

Diisopropyl (PF-3) 

16 

31 

52 

Diallyl 

27 

46 

67 


That di-sec-butyl fluorophosphate is a very potent 
miotic is revealed by the production of marked pupil- 
lary constriction within 10 minutes after the exposure 
of monkeys to 50 mg min/m^ {t = 2 minutes).^®'’ 
Animal data adequate to provide a basis for evalu- 


ating the relative potencies of this compound and of 
PF-3 are not available. Dicyclohexyl fluorophosphate 
also appears to be an effective miotic that produces 
pupillary constriction after a somewhat greater la- 
tency than characterizes the compounds just men- 
tioned. Its potency relative to that of PF-3 is not 
known. 

The high miotic potency of MCE is illustrated by 
observations on animals but quantitative com- 
parisons with the fluorophosphates are not available. 
At high doses MCE can produce conjunctival hemor- 
rhages.®® 

Observations on Human Subjects 

MCE appears to be considerably more potent in 
producing eye effects than any of the fluorophos- 
phates.®® Although a dosage of 0.7 mg min/m® (t = 
2 minutes) was without effect on the eyes, 3.2 mg 
min/m® (t = 2 minutes) produced slight but definite 
miosis. Dosages of 14 to 21 mg min/m® produced a 
severe harassing effect of several days’ duration. The 
action of these dosages was characterized by the fol- 
lowing symptoms, not all of which were observed in 
all the subjects: pin-point constriction of the pupils, 
lasting for several days; severe frontal headache; 
retrobulbar pain, tightness in the chest, and cough- 
ing; pain on focusing on near objects; slight blurring 
of both distant and near objects; slight blurring of 
peripheral visual fields; nausea and vomiting; en- 
gorgement of the bulbar conjunctival, anterior cili- 
ary, and radial iris vessels, and of the vessels at the 
base of the iris; acute ciliary tenderness; and fall in 
intraocular tension. This symptomatology was usu- 
ally almost completely relieved within an hour after 
the instillation of either atropine or hyoscine solu- 
tion, but the effects of the treatment did not persist. 
In the absence of treatment the symptoms became 
most harassing 24 to 48 hours after exposure and 
persisted in gradually decreasing intensity for several 
days thereafter. In the case of one observer exposed 
to 30 mg min/m® (t = 10 minutes), the harassment 
was very severe and, in addition to the effects men- 
tioned above, visual acuity was markedly reduced 
and had not returned to normal 17 days after ex- 
posure. 

Data on the eye effects of MFI are not available. 

PF-3 produces symptoms similar to those caused 
by MCE but is definitely less potent. From the data 
presented below it would appear that exposure to 
40 mg min/m® of PF-3 vapor produces about the 
same effects as exposure to 3 mg min/m® of MCE 


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TOXICOLOGY 


147 


vapor. At larger dosages, 200-400 mg min/m^ of 
PF-3 may correspond roughly to 14 to 20 mg min/nP 
of MCE. 

PF-1 and diethyl fluorophosphate are definitely 
less potent miotics than PF-3. 6fs(Dimethylamido)- 
phosphoryl fluoride is also less potent, probably 
much less so. Di-sec-butyl fluorophosphate appears 
to be somewhat more potent than PF-3 but defi- 
nitely less potent than MCE. 

The observations on which the above statements 
are based may be abstracted as follows. 

1. Ethyl dimethylamidocyanophosphate {MCE). The results 
of one controlled laboratory study are available.®* In addition 
there have been accidents which demonstrate that exposures 
to undetected concentrations of the vapor can produce ex- 
treme pupillary contraction and in addition congestion of the 
eyes.®®!’ n jn other instances a feeling of tightness in the chest 
has accompanied and given warning of the exposure. 

Four subjects exposed in a man-chamber to 0.7 mg min/m® 
(< = 2 minutes) detected the odor of the agent and experienced 
a brief feeling of tightness in the chest. They developed no 
miosis. 

Ten additional subjects were exposed to a dosage of 3.2 mg 
min/m® {t = 2 minutes). Only two noticed any smell. Six ex- 
perienced a very slight feeling of constriction in the chest. 
Slight miosis developed in all after 30 to 60 minutes. 

Ten subjects, some of whom had been exposed 4 hours 
previously in the preceding group, were exposed to 14 mg 
min/m® {t = 2 minutes). The gas was detected faintly by 
smell and those not previously exposed felt a slight tightness 
in the chest. Soon after exposure all subjects had contraction 
of the pupils which persisted for 48 hours. Severe headache 
and pain in the eyes followed unless atropine was administered. 
Vascular injection of the eyeballs was present. Difficulties of 
focusing were experienced. Vomiting on the day after exposure 
occurred in four of the subjects. 

Three additional subjects were exposed to 14 mg min/m® 
(t = 10 minutes). The odor and a feeling of tightness in the 
chest were detected. Pupillary constriction, headache, rhinor- 
rhea, nasal congestion, and other symptoms developed rapidly 
and persisted for several days in the absence of treatment. 
Visual acuity at moderate illuminations was not markedly 
affected. 

Five additional subjects were exposed to 21 mg min/m® 
{t = 10 minutes). They became severely harassed by the 
symptoms that developed. The symptoms and their times of 
onset (minutes, in parenthesis) were tightness in the chest 
(1.5 to 8), coughing (1.5 to 6), pin-point pupils (10), lacrima- 
tion (2 to 10), retrobulbar pain (8 to 19), conjunctival con- 
gestion (2 to 10), “tingling” of the eyelids (6 to 10), rhinor- 
rhea (6 to 120), frontal headache (13 to 18), difficulty of seeing 
distant objects (11,14 — two cases), difficulty in seeing near 
objects (15 — one case), and constriction of the peripheral 
visual fields (15 — one case). 

One subject with one eye protected was exposed to 30 mg 
min/m® {t = 10 minutes). The protected eye was unaffected. 
The pupil of the exposed eye began to contract within 4 min- 
utes and had become fully contracted within 12 minutes. 


Visual acuity in dim light had markedly deteriorated within 
an hour and had not fully recovered 17 days later. Moderate 
conjunctival and severe ciliary congestion had developed 
within 3 hours. The subject was unable to sleep for two nights 
because of severe pain above and behind the exposed eye. 

2. Dimethyl fluorophosphate {PF-1). At low dosages PF-1 
is not so potent a harassing agent as PF-3, nor does the pupil- 
lary constriction which it induces persist as long. Although 
this ester is considerably less readily detected by odor than 
PF-3, it is more irritating to the throat and chest. In subjects 
exposed to nominal concentrations as low as 5.7 fxg/\ (1/10®) 
it produced a tightening sensation in the throat.^®^* No eye 
effects were noted when subjects were exposed, presumably 
for short times, to this concentration or to one four times as 
great. 

At a considerably higher concentration, 114 ^g/l (1/50000), 
the throat sensation was not more marked but eye effects were 
produced: an exposure of 30 seconds’ duration (Ct = 57 mg 
min/m®) produced in five of seven subjects some pupillary 
constriction and discomfort but no spasm of the muscles of 
accommodation; exposures of 1 to 5 minutes’ duration 
{Ct = 114 to 570) produced within 5 to 10 minutes pupillary 
constriction lasting for an hour or more, and, in 50 per cent 
of the subjects, a marked spasm of the muscles of accommo- 
dation. 

3. Diethyl fluorophosphate.'^^ This ester also appears to be 
considerably less potent than PF-3. In twelve subjects 2-min- 
ute exposure to a nominal concentration of 139 fxg/\ {Ct = 
278 mg min/m®) produced throat irritation within 10 to 
30 seconds, then a painless tightening sensation in the chest, 
and finally coughing toward the end of the exposure. Within 
30 to 60 minutes the pupils had partially contracted and their 
reflexes to light and accommodation were absent. There was 
no significant alteration in visual acuity in daylight or in sim- 
ulated twilight, although the sensitive Rangefinder Test 
revealed harassment. The size and reflexes of the pupil had 
returned to normal within 18 hours. At no time was there more 
than minimal congestion of the iris in any of the subjects. 

4. Diisopropyl fluorophosphate (PF-5).®^*^* ®®> ®^^- ^®’ 

79, 84, 100, 104e 

a. First {preliminary) British examination . Ten minutes 
after exposure of two subjects to a nominal dosage of 
246 mg min/m® (0.082 mg /I for 3 minutes), the pupils be- 
gan to constrict and subsequently were reduced to pin- 
point size, with the result that the laboratory appeared 
dim. The observers experienced difficulty and pain in focus- 
ing, eye ache, and headache. A book could be read only if 
held within a few inches of the eye. The miosis and diffi- 
culty of accommodation persisted for 2 to 3 days in the 
case of the older volunteer (over 60 years of age) and for 
almost a week in the younger (28 years). The report does 
not mention extraocular symptoms. 

Upon exposure of two additional subjects to a nominal 
dosage of 82 mg min/m® (0.0082 mg/1 for 10 minutes) the 
effects did not develop for about 30 minutes but then ap- 
peared as described above and persisted for 3 days. The 
subjects could read only with pain and difficulty. Vision in 
dim light was poor. Distant vision was impaired but re- 
covered sometime before near vision had returned to nor- 


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148 


FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


mal. The eyes of one observer were congested for about a 
day beginning 1 day after exposure. 

b. Preliminary American observations.*^’ Upon exposure of 
only the eyes of several subjects to a nominal dosage of 
approximately 300 mg min/nU (0.1 mg/1 for 3 minutes) 
only one subject reported slight subjective eye irritation 
during exposure. Miosis became maximal within 20 to 30 
minutes and pemisted for about a week. The subjects ex- 
perienced difficulty in accommodation and found reading 
painful during the first 2 days; they had less difficulty after 
1 to 2 days in spite of the maintenance of pupillary con- 
traction and the development of irritation (congestion), 
eye ache, and headache. There was only a slight decrease in 
far vision; Snellen charts could be read about as well as be- 
fore exposure. The subjects reported that their night vision 
was poor. Atropine and adrenaline instillations gave relief 
but had to be repeated daily. In two men accidentally ex- 
posed for several hours to low and undetected concentra- 
tions, a viewed object first appeared clearly but then 
rapidly became blurred, accommodation was slightly re- 
duced, and nearsightedness apparently increased.^® 

Four men whose eyes only were exposed to approximate 
dosages of 111 to 210 mg min/m® (0.037-0.070 mg/1 for 
3 minutes) detected no odor and experienced no discom- 
fort during exposure. They subsequently developed miosis, 
difficulty of focusing and blurred vision, eye ache and head- 
ache, conjunctivitis and a gritty sensation in the eye, and 
twitching of the eyelids. Visual acuity as tested by Snellen 
charts was not reduced. Four men accidentally exposed to 
low, undetected concentrations experienced eye effects as 
just described and, in two cases, nausea. There is some evi- 
dence that in two cases visual acuity in dim light was 
reduced.®^ 

c. Second British examination.’^^ Subjects were exposed to 
nominal concentrations of vapor in a large man-chamber 
and subsequently examined for pupil size, pupillary re- 
flexes to light and accommodation, and acuity of near and 
distant vision as tested with Jaeger and Snellen Test Type 
indices both in daylight and in simulated twilight (approxi- 
mately 0.4 footcandle).*’ The general condition of their 
eyes was also examined and their performance on the 
Rangefinder Test ® in ordinary daylight and simulated 
twilight ^ determined. 

All six subjects exposed to 41 mg min/m^ (0.0082 mg/1 
for 5 minutes) complained of throat irritation about 1 min- 
ute after the start of the exposure and of “tightness in the 
chest” after about 1.5 minutes. Three hours later the pupil 
was only slightly contracted and pupillary reflexes to light 
and accommodation were present and normal. The tests 
for visual acuity revealed no significant deterioration 
either in ordinary light or in simulated twilight. The aver- 
age degree of harassment for the group as measured by the 
Rangefinder technique was 36 per cent in ordinary light 
and 50 per cent in simulated twilight. At no time was there 


This level of illumination was far greater than would be 
encountered at night and the tests therefore give no adequate 
measure of the handicaps which the subjects would have 
experienced in night fighting. 

® This technique has been described'* and critically dis- 
cussed.^^® 


congestion of the iris and no subject experienced headache 
or other discomfort. 

Upon exposure to 99 mg min/m* (0.033 mg /I for 3 min- 
utes) all of 18 subjects experienced throat irritation after 
about 50 seconds of exposure and complained of “tighten- 
ing of the chest” within about 1.5 minutes. It took 4 to 
6 hours for maximal miosis to develop, at which time pu- 
l^illary reflexes were absent. The tests for visual acuity (as 
described) revealed no significant change although the 
Rangefinder test indicated 14 per cent harassment with 
ordinary lighting and 100 per cent in simulated twilight. 
Congestive iritis with accompanying headache and photo- 
phobia developed within 18 to 24 hours. Atropine sulfate 
(1 per cent) proved more effective than homatropine (1 per 
cent) in dilating the pupils and relieving the iritis. 

Of 12 subjects exposed to 328 mg min/nU (0.164 mg/1 
for 2 minutes) all experienced throat irritation and a feel- 
ing of tightness in the chest within 30 to 105 seconds. There 
was also some coughing, but no eye irritation, lacrimation, 
or blepharospasm occurred. The pupils were only partially 
contracted 30 minutes after exposure but had contracted 
nearly to pin-point size within 3 hours. Pupillary reflexes 
were then absent. A definite deterioration in acuity for dis- 
tant vision had developed within 30 to 60 minutes after 
exposure and was not notably more marked when tested 
in simulated twilight (see preceding paragraph) than when 
tested at higher levels of illumination. The individual alter- 
ation in near vision was variable at both tested levels of 
illumination but for the group as a whole there was definite 
deterioration. Twenty-four hours after exposure distant 
vision had improved but near vision had deteriorated fur- 
ther. The subjects without exception complained of head- 
ache, the pain being referred to above or behind the eyes 
and being sufficiently intense to interfere with sleep. There 
was well-marked congestive iritis and conjunctival con- 
gestion but no edema of the lids, conjunctiva, or cornea. 
The average degree of harassment for the group as meas- 
ured by the Rangefinder technique was 63 per cent in or- 
dinary light and 100 per cent in simulated twilight. 

Granted that the symptoms caused some discomfort and, 
at night, visual harassment, they were not considered to be 
of a disabling nature in the recorded opinion of the British 
Ophthalmic Panel and Medical Subcommittee.^^® 

d. Third British examination.^* The eyes only of sixteen sub- 
jects were exposed for 5 minutes in a constant-flow device 
to analytically determined dosages of 40 to 250 mg min/m®. 
Subsequent clinical examination included observations on 
pupil size, visual acuity at high and relatively dim illumi- 
nations, the near point of accommodation, the threshold of 
scotopic vision, and the condition of the conjunctiva, 
cornea, and iris. 

In summary, with dosages up to 191 mg min/m* the 
effects produced by the vapor on pupil size and the accom- 
modative mechanism were not considered of serious con- 
sequence. However the three subjects exposed to 250 mg 
min/m* developed a congestive iritis associated with pain- 
ful symptoms and consequently were considered to be 
partially disabled for 3 to 6 days. 

The pupil had contracted to a minimum diameter of 1 to 
2 mm within less than 1 day at all dosages and within 1 
hour at dosages above 116 mg min/m*. The miosis began 


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TOXICOLOGY 


149 


to abate after 2 days at the lower dosages and after 3 days 
at the higher ones, but was not completely relieved for 5 to 
6 days. During the first days prolonged dark adaptation 
resulted in no pupillary dilatation. 

Visual acuity tested with Snellen charts in bright light 
(17 footcandles) showed practically no deterioration. In- 
deed, the uncorrected vision of myopes was improved, as 
a result of the small pupil size. Visual acuity in relatively 
dim light was determined by lowering the illumination of 
the Snellen chart until the smallest type which the subject 
could read at high illumination was no longer legible. Be- 
fore exposure the average illumination recorded for the 
twelve eyes of six observers was 2.8 footcandles (range 
0.32-10.5). Twenty-four hours after exposure to 40 or 
80 mg min/m ^ it was 6.4 footcandles (range 0.32-17). 
This change was not considered consistent or marked. It 
must be emphasized that the tested range of illuminations 
was sufficiently high that cone (not rod) vision was being 
measured, and that the results throw no light on the im- 
pairment which may have been produced in night vision. 

Among subjects exposed to 40 to 191 mg min/m^ the 
near point of clear vision was brought in, indicating in- 
creased ciliary tension. However the absence of serious im- 
pairment of distant vision indicates that any existing 
spasm of the muscles of accommodation was not a serious 
handicap at the light intensities employed in the tests. 

From the changes in pupil size caused by the PF-3 vapor 
one might have expected as much as a 16-fold rise in sco- 
topic visual threshold. Actually the change in threshold 
brightness level, as measured with the Craik Adaptometer 
1 to 2 hours after exposure to 116-191 mg min/m^, was only 
2- to 10-fold (average 5+ fold in six subjects). 

Subjects exposed to 100-191 mg min/m^ generally de- 
veloped conjunctival hyperemia 2 to 3 days after exposure. 
At 250 mg min/m^ the hyperemia was much more severe 
and developed within 24 hours. In addition a marked and 
potentially dangerous congestive iritis, accompanied by 
painful symptoms, made its appearance. 

Examination with the slit lamp revealed no corneal 
changes, nor were changes noted upon opthalmoscopic ex- 
amination in instances where miosis had been abolished 
with a mydriatic. 

Among the subjective symptoms reported by the sub- 
jects were mistiness before the eyes, eye ache, and diffi- 
culty of seeing in the dark. 

Instillation of homatropine (0.43 minim) had to be re- 
peated three times at hourly intervals in order to obtain 
significant pupillary dilatation in two observer who de- 
veloped congestive iritis following exposure to 250 mg 
min/m®. After the third instillation the congestive symp- 
toms were relieved but paralysis of accommodation oc- 
curred and the observers became partially disabled 
because of blurry vision. 

e. American assessment. One subject was exposed 
in a man-chamber to a dosage of 181 mg min/m® {t = 6.7 
minutes), eight subjects to 165 mg min/m® (t = 8.7 min- 
utes), one subject to 290 mg min/m® {t = 10.7 minutes), 
and six subjects to 244 mg min/m® (t = 9 minutes). 

All the men exposed to 165 mg min/m® experienced a 
slight feeling of tightness and constriction in the chest, 
apparent ^ hour after exposure and particularly noticeable 


several hours later. Instances of rhinorrhea, diarrhea, 
nausea, and vomiting (one case) occurred but, except for 
the rhinorrhea, may not have been due to the effects of the 
PF-3. No muscle tremors — a sign which might be ex- 
pected to herald serious systemic poisoning — were ob- 
served. 

Of the men exposed to 244 mg min/m® (0.027 mg/1 for 
9 minutes), five of six experienced a fleeting feeling of chest 
constriction while in the chamber. This returned and per- 
sisted for 2 days, being accompanied by coughing in two 
cases. All the subjects developed rhinorrhea within an hour 
after the exposure. Only one developed nausea, and he 
vomited twice. There were no abdominal cramps or muscle 
tremors. One volunteer exposed to 290 mg min/m® de- 
veloped constant nausea for a day following exposure, ex- 
perienced abdominal cramps, and exhibited increased nasal 
secretion. He had no muscular tremors and felt no chest 
constriction. 

The majority of men in both groups had diminished dis- 
tant vision, which was caused by a spasm of the muscles of 
accommodation. Although the resultant false myopia 
measured between 1.75 and 6.5 diopters, because of the 
small pupil size the visual acuity was not diminished 
greatly. The greater part of the diminution of distant vi- 
sion had developed within 45 minutes after exposure. Fur- 
ther deterioration occurred at 3 hours in some cases. Re- 
covery occurred at 2 to 7 days, being slightly more rapid 
in the subjects exposed to the smaller dosage than in those 
exposed to the larger. 

Maximal miosis developed within 10 to 15 minutes after 
exposure. Among the men exposed to 165 mg min/m®, the 
pupils began to relax after 1 to 3 days and attained normal 
size and activity after 3 to 9 days. Among those exposed to 
244 mg min/m® relaxation did not begin until after the 
third day and complete recovery required 5 to 11 days. 

All the volunteers showed a diffuse conjunctival injec- 
tion which required 5 days to clear up. 

Concurrently with the development of pupillary con- 
striction and spasm of accommodation, the near point of 
accommodation moved to within 3 to 6 cm from the cornea, 
and it became increasingly difficult for the men to focus 
after gazing into infinity. Small type could be read but 
several seconds were required before it could be seen 
clearly. Without exception the men complained of intense pain 
when they attempted to perform visual tasks within 18 inches. 
Recovery of the untreated eyes gradually occurred over an 
average of 3.5 days after exposure to the lower dosage and 
4.5 days after the larger. 

Except for one man who exhibited a transient rise in in- 
traocular tension, all displayed a subnormal tension for 
several days. 

A performance test (in daylight) showed no decrease in 
efficiency of marksmanship and all of the men felt that 
they could competently discharge such military tasks as 
guard duty, vehicle driving, and rifle firing. 

The reports state that prolonged questioning failed to elicit 
any symptoms of defective night vision, all the volunteers 
feeling that their visual acuity at night was proportional 
to that in the day. This statement is at variance with the 
results obtained in other tests and observations. It would 
not be anticipated that the vision of men with maximally 


SECRET 


150 FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 



Table 4. 

Summary of toxicities. 




Compound 

Mouse 

L(Ct)so in mg min/m® 

(10 min nominal) 

Range for all 
Monkey tested species 

Increase of 
L(Ct) 5 Q with 
increase of 
exposure 
time 

LDoo 

Rabbit, 

intra- 

venous 

(mg/kg) 

Mouse, 

percu- 

taneous 

Ethyl dimethylamidocyanophosphate (MCE) 

380 

250 

200-1,000 

Slight 

0.1 ± 

1± 

Isopropyl methanefluorophosphonate (MFI) 

250 

150 

100-300 

Definite 

0.02 

1 + 

Isopropyl ethanefluorophosphonate 

330 

200 

150-700 ± 

Definite 


1.7 

Dimethyl fluorophosphate (PF-1) 

2,600 

. . . 

2,500- >12,000 

Marked 

3 

36 

Diethyl fluorophosphate 

8,200 

. . . 

7,000- >14,000 

? 

. . . 

35 

Diisopropyl fluorophosphate (PF-3) 

5,900 

600 

600- >8,000 

Slight 

0.4 

72 

Di-sec-butyl fluorophosphate 

5,200 

250 ± 150 

250- >18,000 

? 

. . . 

. . . 

Dicyclohexyl fluorophosphate 

1,100 

. . . 

1,000-8,000 

? 

. . . 

. . . 

5fs(Dimethylamido)phosphoryl fluoride 

950 


950- >4,000 

? 

3± 



contracted pupils would be normal at illuminations suffi- 
ciently low to confine visual function to the rods. 

The serum cholinesterase concentration of all the sub- 
jects was reduced by the exposure to PF-3 to 1 to 5 per cent 
of the normal value. 

f. Additional accidental exposures.^®-'®-!®® Workers acciden- 
tally exposed to undetected concentrations at the American 
pilot plant developed extreme miosis of 1 week’s duration. 
Difficulty of night vision was stressed.^® 

In a report on a similar incident at the British pilot plant 
emphasis was placed on pupillary contraction, blurring of 
vision, especially in artificial light, headache, and tight- 
ness in the chest. In another incident '® undetected ex- 
posures to vapor produced miosis, poor vision in dim light, 
difficulty in focusing, twitching of the eyelids, nasal dis- 
charge, and (in some cases) conjunctivitis. There was no 
mention of headache or chest symptoms. 

5. Di-sec-bntyl fluorophos'phate}'^^ This ester has been 
given only preliminary tests with four human subjects. Upon 
exposure to a nominal concentration of 1/10® {Ct = approxi- 
mately 45 mg min/m®) all noticed a tightness across the chest 
but three of the four felt that it was not sufficient to call for a 
respirator. About 5 minutes after the subjects left the cham- 
ber, miosis set in, became intense, and persisted for 5 days. 
Comparison with the results obtained with PF-3 at compa- 
rable and somewhat greater dosages 79,io4c ^v’ould indicate that 
the di-sec-butyl ester may be the more potent miotic agent. 

6. bis(Dimethylamido)phosphoryl fluoride}^^ Exposure of 
four volunteer subjects to about 45 mg min/m® (7.3 /zg/l or 
1/10®, for 5 to 7 minutes) produced no observable ocular or 
systemic effects. This compound is therefore less effective, 
perhaps very much less effective, than PF-3. 

9.3.3 Toxicity 

Inhalation and Injection Tonicities 
Toxicity data for the more intensively studied Tri- 
Ions, fluorophosphates, and dialkylamidophosphoryl 
fluorides are given in Tables 5 through 17 and are 
summarized in Table 4. It is apparent that the Tri- 
Ions are the most toxic volatile agents considered in 


Table 5. Toxicity of ethyl dimethylamidocyanophos- 
phate (MCE) by inhalation. 

The animals were totally exposed to the vapor of the 
agent. Concentrations were nominal except when other- 
wise designated. 


Species 

Exposure 

time 

(min) 

L{CtU 

(mg min/m®) 

Number 

of 

animals 

Reference 

Mouse 

2 

400 

100 

69d 


5 

385 

100 

69d 


5 

500-750 

22 

104s 


10 

380 

460 

69d,e 


10 

220* 

140 

87 


10 

500-750 

18 

104s 


20 

420 

100 

69d 


30 

420 

100 

69d 


60 

670* 

120 

87 


120 

840* 

60 

87 

Rat 

5 

750-1,000 

14 

104s 


10 

750-1,000 

10 

104s 


10 

500-1,500 

14 

69c,e 


10 

304* 

230 

87 


20 

385* 

54 

66k 


60 

620* 

60 

87 


120 

1,200* 

120 

87 

Guinea pig 

5 

1,000 + 

6 

104s 


10 

1,000-2,000 

6 

104s 


10 

393* 

81 

87 


10 

500-1,500 

12 

69c,e 


60 

740* 

56 

87 


120 

1,500* 

48 

87 

Rabbit 

10 

1,000* 

15 

87 


10 

>4,000 

6 

104s 


10 

>2,000 

4 

69c,e 


10-62 

840* 

55 

66h 

Cat 

7.5 

300-800 

3 

104s 


10 

250 

8 

69c,e 

Dog 

10 

400 

4 

69c, e 

Goat 

10 

700* 

9 

87 


14-23 

400-700* 

10 

66h 


13-129 

765* 

30 

66k 


20 

1,400* -t 

38 

66k 

Monkey 

5-10 

400 + 

5 

104s 


10 

250 

4 

69c,e 


10 

180* 

3 

87 


* Analytically determined concentration 
t Angora goats. 


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TOXICOLOGY 


151 


Table 6. LDso’s of ethyl dimethylamidocyanophos- 
phate (MCE). 

The figures in parentheses are the number of animals 
used. 


Route of 
administration 

Species 

Approximate 
LDao (mg /kg) 

Reference 

Intravenous 

Mouse 

0.15 

(15) 

69c 


Rat 

0.066 

(35) 

66 h 


Rabbit 

0.0625 

(46) 

66 h 



0.18 

(14) 

87 



0.125 

(15) 

104s 


Dog 

0.084 

( 20 ) 

66 i 



0.146 

(9) 

69c 

Subcutaneous 

Mouse 

0.4 

(25) 

87 


Rat 

0.3-0.4 

(42) 

87 


Guinea pig 

0.2 

( 20 ) 

87 


Rabbit 

0.5 

(30) 

87 

Percutaneous 

Mouse 

1.0 

(70) 

69c 



>4 

( 20 ) 

66 g 


Rat 

18-35 

(47) 

87 


Guinea pig 

35 

(43) 

87 


Rabbit 

2.5-3.0 

(5) 

69g 



3.3 

(60) 

69h 



35 

(19) 

87 


Dog 

30-50 

(4) 

69c 

. 

Goat 

>5 

( 2 ) 

66 g 



1.1 

( 21 ) 

66 h 



3 

(17) 

87 


Monkey 

9.3 

( 6 ) 

69c 

Per os 

Rat 

3.7 

(107) 

66 h 



8 

(26) 

87 


Rabbit 

16.3 

(51) 

66 h 


Dog 

5-11 

( 12 ) 

66 h 

Table 7. Toxicity of 

isopropyl 

methanefluorophos- 


phonate (MFI) by inhalation. 


The animals were totally exposed to the vapor of the 
agent. All concentrations were nominal. 


Species 

Exposure 

time 

(min) 

L(Ctho 
(mg min/m^) 

N umber 
of 

animals 

Reference 

Mouse 

5 

230 

100 

69e 


10 

250 

100 

69e 


10 

150-250 

22 

104t 


15 

345 

120 

69e 


20 

360 

100 

69e 


30 

420 

100 

69e 

Rat 

10 

300 

18 

69d,e 


10 

150-250 

12 

104t 

Guinea pig 

10 

180 

18 

69d,e 


10 

150—250 

12 

104t 

Rabbit 

10 

120 

6 

69d,e 


10 

150-250 

5 

104t 

Cat 

10 

100 

10 

69d,e 

Dog 

10 

100-150 

8 

69d,e 

Monkey 

10 

150 

5 

69d,e 


this volume. The fluorophosphates are considerably 
less toxic, although the potency of PF-3 and di-sec- 
butyl fluorophosphate for the monkey approaches 
that of the Trilons. The limited data for MFI indi- 


Table 8. LDso’s of isopropyl methanefluorophosphonate 
(MFI). 

The figures in parentheses are the number of animals 
used. 


Route of 
administration 

Species 

Approximate 
LD 50 (mg/kg) 

Reference 

Intravenous 

Rat 

0.045 

(30) 

66 i 


Rabbit 

0.016 

(44) 

66 i 

Percutaneous 

Mouse 

1.08 

(40) 

69d 


Rabbit 

0.925 

(19) 

66 i 

Per os 

Rat 

0.55 

( 66 ) 

66 i 


Table 9. Toxicity of isopropyl ethanefluorophosphonate 
by inhalation. 

The animals were totally exposed to the vapor of the 
agent. All concentrations were nominal. 


Species 

Exposure 

time 

(min) 

L(Ctho 
(mg min/m*) 

Number 

of 

animals 

Reference 

Mouse* 

5 

245 

80 

69e 


10 

330 

120 

69d,e 


10 

350-1,000 

8 

104t 


30 

570 

60 

69e 

Rat 

10 

260 

6 

69e 


10 

<350 

4 

104t 

Guinea pig 

10 

>210 

6 

69e 


10 

350-1,000 

4 

104t 

Rabbit 

10 

230 

4 

69e 


10 

350-1,000 

4 

104t 

Cat 

10 

170 

6 

69e 

Dog 

10 

230 

4 

69e 

Monkey 

10 

210 

3 

69e 


* Subcutaneous LDho (8 mice) = approx. 0.4 mg/kg. Percutaneous 
LDbo (40 shaved mice) =1.7 mg/kg.®®*^ 


cate that the species variation in susceptibility is not 
pronounced. On the other hand the animal species 
exhibit considerable variation when MCE, and par- 
ticularly the fluorophosphates, come into considera- 
tion.®^ This variation makes estimates of the human 
lethal dosage precarious. In the case of PF-3 com- 
parison of the systemic effects produced upon ex- 
posure of human subjects (see preceding section) and 
of monkeys to dosages in the order of 

300 to 400 mg min/m^ indicate clearly that man is 
the more resistant species. Man was affected but not 
prostrated, whereas the monkeys were severely pros- 
trated and some were killed. How much more re- 
sistant man is to PF-3 than the monkey is not known, 
nor does the same relationship necessarily hold for 
the Trilons. 

d The high L(Ct)ooS of PF-1 and PF-3 (possibly also 
MCE) for the rabbit are due largely to inhibition of respira- 
tion. When inhibitory respiratory reflexes are suppressed, or 
when the agents are injected, the rabbit is not found to be 
excessively resistant.^s 4 -j '53 


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152 


FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


Table 10. Toxicity of dimethyl fluorophosphate (PF-1) 
by inhalation. 

The animals were totally exposed to the vapor of the 
agent. All concentrations were nominal. Injection and 
percutaneous toxicity figures are given in the footnotes. 
Except for the mouse L(C05o’s, the figures are very rough 
approximations based on only a few animals of each 
species. 


Species 

Exposure 

time 

(min) 

L(C050 

(mg min/m®) 

Reference 

Mouse* 

1 

1,200 

261 


2 

1,740 

26h 


10 

2,550 

11 


10 

3,000 

49 


30 

5,000 ± 

26f 


120 

>5,000 

26f 

Rat 

1 

1,800 ± 

26f,l 


10 

3,000-6,000 

26a, 104b 

Guinea pig 

1 

7,000 ± 

26f,l 


0.5-4 

8,000 ± 

26f 

Rabbitf 

1 

>12,000 

26f, 104b 

Catt 

1 

6,000 + 

261 

Dog§ 

1 

6,000 ± 

261 

Goat 

3-5 

20,000 ± 

26f 

House fly 

10 

<30 

261 

Mosquito II 

10 

<30 

261 


* Mouse intravenous LDso = 0.45 mg/kg.*®® Mouse intraperitoneal 
LDso = 3-4 mg/kg.^^ Mouse percutaneous LDio (70 mice) = 0.72 
mg/animal, or approx. 36 mg/kg. 

t Rabbit intravenous LDso = 2-4 mg/kg.*®® 
t Cat intravenous LDso =1.5 mg/kg.^*‘ 

§ Dog intravenous LDio = 1-2 mg/kg.'®® 

II Aedes aegypti. 

Table 11. Toxicity of diethyl fluorophosphate by 
inhalation. 

The animals were totally exposed to the vapor of the 
agent. All exposure times were for 10 minutes and all 


concentrations were nominal. Except 
L(Ct)ooS, the figures are very rough 
based on 6 to 18 animals per species. 

for the mouse 
approximations 

Species 

LiCtho 
(mg min/m^) 

Reference 

Mouse* 

8,200 

11 


4,100 

49 


4,000-6,000 

104b 

Rat 

7,000-14,000 

26b, 104b 

Guinea pig 

7,000-14,000 

26b, 104b 

Rabbit 

> 14,000 

104b 


* Mouse percutaneous LDso (60 mice) = 0.70 mg/animal, or approx. 
35 mg/kg.4» 


As indicated by the data of the toxicity tables, the 
“rate of detoxification” as measured by the increase 
of the lethal dose with increase of time of its admin- 
istration, is marked for PF-1, moderate for MFI 
and isopropyl ethanefluorophosphonate, and slight 
but definite for MCE and PF-3. More detailed data 
bearing on the rate of detoxification as determined 


Table 12. Toxicity of diisopropyl fluorophosphate 
(PF-3) by inhalation. 

The animals were totally exposed to the vapor of the 
agent. All concentrations were nominal. Except for the 


mouse and rat L(C 05 o’s, the figures are rough approxi- 
mations based on relatively few animals per species. A 
total of 39 monkeys were exposed. 

Species 

Exposure 

time 

(min) 

UCtho 
(mg min/m^) 

Reference 

Mouse 

1 

4,000 

104e 


2 

3,800 

104e 


5 

2,700 

104e 


10 

3,500 

104e 


10 

5,500 

49 


10 

5,900 

26c, p 


30 

4,500 

104e 


100 

>6,400 

26p 

Rat 

1 

4,200 

104h 


2 

3,600 

104h 


5 

2,850 

104h 


10 

2,800 

104h 


30 

4,500 

104h 

Guinea pig 

10 

>8,200 

104b 

Rabbit 

10 

(8,000 ±) 

104b 

Dog 

10 

5,000 ± 

83 

Goat 

10 

6,000-7,000 

83 

Monkey 

2 

500-800 

261 


2-15 

500 ± 

63, 64 


10 

800 ± 

83 


100 

1,000-2,000 

26p,r 


Table 13. LDsoS of diisopropyl fluorophosphate (PF-3). 

Route of 
administration 

Species 

Approximate 
LDso (mg/kg) 

Reference 

Intravenous 

Rabbit 

0.3-0.4 

67b 



0.4 ± 

53 



0.5-0.75 

32a 


Cat 

<3 

33a 


Goat 

0.8 + 

53 


Monkey 

0. 1-0.2 

48, 66a, 67f 

Intramuscular 

Rat 

2- 

32b 


Rabbit 

0.75-1.0 

67b 

Subcutaneous 

Mouse 

4± 

86, 104e 


Rat 

3± 

86 


Rabbit 

1± 

86 


Dog 

3± 

86 


Goat 

1 + 

86 

Percutaneous 

Mouse 

72 + 

49 



(1.45 mg/mouse) 


Per os 

Mouse 

36.8 

68a 



2± 

86 


Rat 

5-10 

26r 



6± 

86 


Rablnt 

9.8 

68b 

By eye 

Rabbit 

1.4 

32a 


by inhalation and injection experiments will be found 
in the references cited in the tables. Other references 
are also pertinent.‘^®hg,43,53,55 

Both the Trilons and the fluorophosphates are 


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TOXICOLOGY 


153 


Table 14. Toxicity of di-sec-butyl fluorophosphate by 
inhalation. 

The animals were totally exposed to the vapor of the 
agent. All concentrations were nominal. Except for the 
mouse LfCOso’s, the figures are very rough approxima- 
tions based on 2 to 23 animals of each species. 


Species 

Exposure 

time 

(min) 

L{Ct),o 

(mg min/m^) 

Reference 

Mouse 

10 

5,140 

26r 


10 

5,400 

104i 

Rat 

10 

4,000-10,000 

26r, 104i 

Guinea pig 

10 

>18,000 

26r, 104i 

Rabbit 

10 

5,000-10,000 

26r, 104i 

Cat 

10 

6,000 ± 

26r 

Dog 

10 

4,000-6,000 

26r 

Monkey 

2 

100-400 

26q,r 


Table 15. Toxicity of dicyclohexyl fluorophosphate by 
inhalation. 

The animals were totally exposed to the vapor of the 
agent. All exposures were for 10 minutes and all concen- 
trations were nominal. Except for the mouse L{Ct)ioS, 
the figures are very rough approximations based on 2 to 
20 animals per species. 


Species 

L{Ct)5o 
(mg min/m®) 

Reference 

Mouse 

800 

1041 


1,100 

26n 

Rat 

1,200 ± 

26n, 1041 

Guinea pig 

6,000-10,000 

1041 

Rabbit 

1,200-2,800 

26n, 1041 

Dog 

1,000-1,400 

261, 26n 


Table 16. Toxicity of 6fs(dimethylamido)phosphoryl fluoride. 


Species 

Approximate L{Ct)i,Q 
Nominal, t = 10 min 

(mg min/m^) 
Reference 

Intravenous 

Approximate LDso (mg/kg) 
Subcutaneous Per os 

Reference 

Mouse 

950 

26j 


1 

2± 

86, 104o 

Rat 

2,000-4,000 

26j, 104o 


0.3-0.4 

1± 

86 

Guinea pig 

>4,000 

26j, 104o 


2± 

4± 

86 

Rabbit 

>2,000 

104o 

3± 

6± 

3± 

86, 104o 

Cat 





2± 

86 

Goat 




2± 


86 

Monkey 





>1 or 2 

86 


“quick-kill” agents. Although occasional deaths are 
delayed for 1 or 2 days, most lethally poisoned ani- 
mals die within 2 hours after exposure, and the ma- 
jority during or within a few minutes after exposure. 
Detailed statements may be found in the references 
cited in the toxicity tables. A special study has shown 
that PF-1 and PF-3 are only slightly slower in speed 
of action than hydrogen cyanide (AC), although the 
lower volatilities of the fluorophosphates would make 
high concentrations relatively difficult to attain in 
the field. 

Symptoms and Pathology 

The symptoms produced by exposure to the Tri- 
Ions and fluorophosphates are those which character- 
ize the nicotinic and muscarinic actions of parasym- 
pathomimetic agents in general. There are also 
evidences of central nervous stimulation. Although 
there are variations according to species, agent, and 
dosage, frequent mention has been made of the fol- 
lowing: lacrimation and salivation; apprehension; 
coughing, dyspnea, and gasping; hyperexcitability, 
incoordination, and ataxia; tremor, muscular twitch- 
ings, and convulsions; sometimes bronchospasm, 
pilomotor stimulation, urination, and defecation; 


general weakness and depression; and finally cessa- 
tion of respiration. Detailed descriptions for the 
various agents and species may be found in the refer- 
ences cited in the toxicity tables (see also the refer- 
ences given under the section “Protection and Treat- 
ment”). 

Respiratory failure is probably the usual primary 
cause of death. However, the action of the agents 
as revealed, for instance, by a study of PF-3,^^“ 
clearly involves most of the important systems in the 
body and the weakest link in the chain of events 
leading to death is questionable. One point of view 
is that bronchospasm may be important in some 
species, including man. This is not true in the cat.^^ 
Because of the early time of death, pathologi- 
cal changes frequently are not conspicuous at au- 
topsy.^®’^-®-*^-®^-^®'^ Dicyclohexyl fluorophosphate, 
which seems to act somewhat more slowly than the 
other fluorophosphates, has been found to produce 
in rabbits a marked pulmonary edema and edema of 
the perivascular connective tissue, marked pulmo- 
nary hyperemia, large areas of atalectasis, hepatic 
congestion and incipient central atrophy, and slight 
lymphorhexis.^®'" The action of (dime thy lamido)- 
phosphoryl fluoride is slower still and the pathologi- 


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154 


FLUOROPHOSPHATES AND PHOSPHORUS-CONTAINING COMPOUNDS 


Table 17. Toxicity of vapors through the skin (body only exposures). 




Exposure 

Dosage {Ct in mg min/m^) 




time 

Nominal 

Analytical 



Agent 

Species 

(min) 

cone. 

cone. 

Mortality 

Reference 

Dimethyl fluorophosphate (PF-1) 

Mouse 

10 

124,000 

122,000 

6/6 

26d 



10 

51,600 

48,200 

3/6 

26d 



15 

13,000 

12,600 

0/6 

26d 

Ethyl dimethylamidocyanophosphate 

Mouse 

10 

3,850 

2,500 

L(Ct)50 

69c, d 

(MCE) 


10 

1,000 

750* 

LlCt)io 

69c 



60 

6,060 

3,900 

L{CtU 

69d 


Guinea pig 

16 

11,200 

6,100 

0/6 

69c 


Dog 

16 

11,200 

6,100 

0/1 

69c 



210 

45,400 

29,000 

0/1 

69d 



227-360 


80,000 + 

L{CtU 
(8 animals) 

66k 


Rabbit 

77-282 


19,000 ± 

L{CtU 
(36 animals) 

66h 

Isopropyl methanefluorophosphonate MFI 

Mouse 

16 

8,720 


1/20 

69e 

6is(i8-Chloroethyl) sulfide (H) 

Mouse 

10 


3,500 

L{Ct)5o 

15 


Rabbit 

13.5 


2,900 

0/1 

15 



18 


4,000 

0/1 




32 


5,800 

1/1 




35 


8,000 

1/1 




60 


13,400 

0/1 




80 


20,500 

1/1 



Dog 

60 


6,550 

0/1 

15 



60 


9,600 

1/1 




30 


15,400 

1/1 




60 


17,600 

1/1 




60 


24,600 

1/1 


tris( /3-Chloroethyl )amine (HNS) 

Mouse 

10 


860 

L{CtU 

15 


Rabbit 

47-140 


>5,500 

L{CtU 

26t,u 


Dog 

30 


13,300 

0/1 

15 



45 


14,500 

0/1 




75 


21,400 

1/1 




100 


51,600 

1/1 



* Skin of mice shaved. 


cal changes are somewhat different. Attention has 
been directed to marked pleural effusion, pulmonary 
edema and hyperemia, and inflammation of the sub- 
mucosal layer of the tracheal and broncheal epi- 
thelium.2®j’’"'*® The references cited in the toxicity 
tables should be consulted for more detailed patho- 
logical information. 

Effects on and through the Skin 

Neither the Trilons nor the fluorophosphates exert 
a vesicant action. With regard 
to absorption of the agents through the skin, the 
data given in Table 17 suggest that vapor dosages 
reasonably attainable in the field would not produce 
significantly severe systemic effects percutaneously 
in the cases of the larger animals nor, presumably, in 
man. Moreover, ordinary clothing can be expected 
to afford some protection against the vapors; CC-2 
impregnated clothing, considerable protection; and 
carbon clothing, virtually complete protection.®®*^-® 
On the other hand, liquid contamination of the skin 


with MCE or MFI is potentially very dangerous 
(see Tables 6 and 8).®®*"-* In the case of MCE rapid 
removal of the liquid by blotting is effective treat- 
ment. Apparently chloramides do not react readily 
with MCE. Consequently antigas ointments are of 
limited value except in so far as their application can 
facilitate the removal of the agent by solvent or me- 
chanical action. In experiments with rabbits it was 
found that interposition of a single layer of plain 
herringbone twill increased by 6- to 8-fold the dose 
of MCE that must be applied to the skin to cause 
death. A single layer of CC-2 impregnated cloth in- 
creased the dose 10- to 12-fold; two layers of this 
cloth, 20-fold; and one layer of carbon cloth, 15- 
fold. ®®‘'-* Thus clothing, particularly protective cloth- 
ing, is of considerable value in preventing the 
absorption of lethal doses of this agent. 

Protection and Treatment 
Numerous substances and procedures for prophy- 
laxis and therapy of the systemic effects of fluoro- 


SECRET 


TOXICOLOGY 


155 


phosphate and Trilon poisoning have been inves- 

these the injection of atropine and magnesium sulfate 
seems to offer the most promise and has been recom- 
mended for use in the event of human poisoning.®®‘'®^® 
These therapeutic agents suppress the autonomic 
symptoms. Injection of Nembutal in addition will 
control the convulsions which occur in MCE poi- 
soning.®®*'*^ However, in severe poisoning the action 
of these drugs will merely delay but not prevent 
death. In any event it is essential that therapy be 
instituted promptly. Adequacy of protection by the 
gas mask has been mentioned, as have been methods 
of treating eye effects and of preventing percutaneous 
absorption of liquid contamination. 


Physiological Mechanism 

In 1941 and 1942 British workers reported that 
the dialkyl fluorophosphates are very potent inhibi- 
tors of cholinesterase.*®®’*®^^’*' Since that time exten- 
sive studies have been made on the clinical pathology 
and biochemistry of action of these compounds,^®®’®’ 
33,43-49,53,54,66,67 more recently of the Trilons, 
which have also proved to be potent anticholines- 
terases.®®®’*'’^’®^’®^®’*’*'’' The results have already begun 
to appear in the open literature and need not be re- 
viewed here. It is obvious that the agents will be 
of great value as tools in physiological and biochemi- 
cal research. Their possible use in the treatment of 
myasthenia gravis has also been under investi- 
gation. 


SECRET 


Chapter 10 

METHYL FLUOROACETATE AND RELATED COMPOUNDS 

By Birdsey Renshaw and Marshall Gates 


10.1 INTRODUCTION 

R eports that methyl fluoroacetate is highly 
toxic were received from Polish investigators 
by the British in 1942 and prompted extensive stud- 
ies in the United Kingdom and United States. Flu- 
oroacetic acid and many simple derivatives including 
salts and esters, /3-fluoroethanol and its esters, and 
salts and esters of 7 -fluorobutyric acid, 7 -fluoro-/ 3 - 
hydroxybutyric acid, and 7 -fluorocrotonic acid, 
proved to be highly toxic by inhalation, injection, 
and ingestion. These compounds produce death, usu- 
ally after a latency of one-half to several hours, by 
action on the heart or central nervous system. 

Compounds of this group are not seriously con- 
sidered for large-scale use in chemical warfare at the 
present time because: ( 1 ) although very toxic for 
some species, the human lethal and incapacitating 
doses are believed to be comparable to, or consider- 
ably greater than, those of the currently standardized 
persistent and non persistent agents; ( 2 ) the stable 
derivatives do not possess sufficiently high vapor 
pressures to be dispersed from available munitions 
in high concentrations as nonpersistent agents; and 
( 3 ) the gas mask affords adequate protection. 

The salts of fluoroacetic and related toxic acids 
are nonvolatile, stable in aqueous solution, and ap- 
proximately as toxic when administered orally as 
when injected. They are, therefore, potential water 
poisons in warfare and are proving to be highly ef- 
fective bait poisons for rodents. 

® Based on information available to Division 9 of the Na- 
tional Defense Research Committee [NDRC] as of October 
1, 1945. 

Attention is directed to a recent paper by J. S. C. Marais, 
entitled M onofluoroacetic Acid, The Toxic Principle of ^^Gif- 
blaar” Dichapetalum cymosum {Hook) Engl., Onderstepoort 
Journal of Veterinary Science and Animal Industry 20, 67-73 
(1944). The early Dutch settlers in South Africa gave the 
name “Gifblaar” to a plant the leaves of which are poisonous 
to livestock. A number of toxicological and chemical studies 
have been made in South Africa since about 1900, and it is 
apparently a remarkable coincidence that the active principle 
was being identified there at the same time that fluoroacetic 
acid derivatives were being actively studied as potential 
chemical warfare agents in the United Kingdom and United 
States. Although the South African literature corroborates 
many of the chemical and toxicological findings summarized 
in this chapter, a cursory survey fails to reveal data permitting 
an independent estimation of the human lethal dose. 


The compounds of this group selectively poison 
enzyme systems and as inhibitors will be of value in 
the study of intermediary metabolism. 

10.2 Synthesis and Properties 

Approximately 160 aliphatic fluorine compounds 
have been prepared by NDRC and British investi- 
gators for evaluation as chemical warfare agents. 
The compounds, their physical properties, and refer- 
ences to their synthesis and toxicity are listed in 
Table 1. 

10.2.1 Synthesis 

In general, the syntheses have been effected by the 
fluorination of corresponding chlorine and bromine 
compounds by treatment with metallic fluorides, 
usually anhydrous potassium fluoride, less frequently 
silver fluoride, mercuric fluoride, or antimony fluo- 
ride, according to known procedures. 

Application to the fluorinated compounds of 
standard synthetic methods has resulted in a variety 
of derivatives including representatives of most of 
the common aliphatic types. 

The methods ma;y be illustrated by the following 
examples. 

1. Methyl fluoroacetate i9-36a,9o,92a been pre- 
pared on a large laboratory scale (50 lb) by heating 
methyl chloroacetate under pressure with anhydrous 
potassium fluoride at 220 C for 5 hours. The product 
is distilled directly from the pressure vessel and is 
purified by fractionation. Yields in the neighborhood 
of 75-77 per cent are obtained. 

The compound is a colorless mobile liquid with a 
faint ester-like odor. Unlike the other haloacetates, 
it has no lacrimatory properties. It boils at 104.5 C, 
freezes at —35 C, and is soluble in water to the extent 
of about 15 per cent. Its physical properties have 
been thoroughly investigated. 

2. Sodium fluoroacetate, 1 9 - 22,926 because of its prom- 
ise as a rodenticide, has been prepared on a much 
larger scale than has any other member of the fluoro- 
acetate series. Complete pilot plant conditions were 
worked out during the course of preparing 1,000 lb 
for use in experimental rodent-control projects. It is 
prepared by saponification of ethyl fluoroacetate 


156 


SECRET 


INTRODUCTION 


157 


Table 1. Aliphatic fluorine compounds examined as candidate chemical warfare agents. 

The compounds are arranged in three major categories in the following sequence: (1) compounds containing not 
more than one fluorine atom attached to any carbon atom; (2) compounds containing two fluorine atoms attached to any 
one carbon atom; and (3) compounds containing three fluorine atoms attached to the same carbon atom. Within each major 
category compounds are arranged in sequence according to the following types: hydrocarbons, alcohol derivatives, amines, 
carbonyl derivatives, and acid derivatives. 

The following abbreviations are used: n^D, refractive index at < C; density in g/ml at < C; specific gravity at 
U C in reference to water at h C; mp, melting point in C; bpp, boiling point in C at p mm Hg; vp‘, vapor pressure in mm Hg 
at < C; and vob, saturation concentration (volatility) in mg/1 at t C. 

Centigrade scale is used throughout the table. 


Compound 

Reference 

to 

synthesis 

Physical properties 
Property Reference 

Reference to 
toxicity 
data 

1 . l-Chloro-2-fluoroethane 

19, 92e 

bp760 

52-53° 

19 

13, 91f 

2. l-Bromo-2-fluoroethane 

92g 

bp760 

71-73° 

31c 

13 

3 . spw-Dichlorodifluorodinitroethane 



1.708 

52 

52 



mp 

12-18° 

52 




bp35 

55-56° 

52 




voP^ 

70.1 

52 


4. tert-Buty\ fluoride 

3, 19 

bp760 

14.5-16° 

3 

13 

5. /3-Fluoroethanol 

19, 92c 


1.3618 

14 

13, 91c, 92c 




1.0913 

14 




bp745 

99-100° 

14 




VOp5 

74.8 

14 


6. Methyl /S-fluoroethyl ether 

91f 

bp 

ca. 60° 

91f 

91f 

7. Chloromethyl /3-fluoroethyl ether 

19 

bp25 

35-40° 

19 

13 

8. /3-Chloroethyl /3-fluoroethyl ether 

19 

bp2o 

55-58° 

19 

13 

9. /3-Fluoroethyl /3-hydroxyethyl ether 

19 

riD^® 

1.4050 

19 

13 



bp^ 

61-62° 

19 


10. Methyl /3-fluoroethoxyacetate 

19 

bp^® 

85-88° 

19 


11. /3-Fluoroethyl phenyl ether 

92f 

mp 

41 

92f 

91h 



bpi7 

92.5° 

92f 


12. 2 '-Fluoro-2 ,4-dinitrophenetole 

19 

mp 

89-91° 

19 

13 

13. /3-Fluoroethyl /3-naphthyl ether 

92g 

mp 

49.5-50° 

92g 

91h 

14. bzs(/3-Fluoroethyl)formal 

19 


1.3809 

14 

13 



bp3o 

75-76° 

14 




VOp5 

10.23 

14 


1 5 . tns{ /3-Fluoroethyl )orthof ormate 

19 


1.3946 

14 

13 




1.2316 

14 




bp20-21 

126-128° 

14 




VOp5 

0.330 

14 


16. /3-Fluoroethyl acetate 

92e 

bp 

118-119° 

92e 

91f 

17. /3-Fluoroethyl chloroacetate 

92g 

bpi® 

78-79° 

92g 

91h 



bp760 

178° 

92g 


18. /3-Fluoroethyl trichloroacetate 

19 

bp^® 

84-87° 

19 

13 

19. /3-Fluoroethyl propiolate 

25 


1.4340 

25 

20 




1.2465 

25 


20. /3-Fluoroethyl e-bromocaproate 

92k 

bp'® 

142° 

92k 

92k 

21. his(/3-Fluoroethyl) acetylenedicarboxylate 

19 

mp 

54-55° 

19 

13 

22. 5fs(/3-Fluoroethyl) chloromaleate (or fumarate) 

19 

bp' 

125-127° 

19 

13 

23. /3-Fluoroethyl N-methjdcarbamate 

19, 30 

bp2o 

91-94° 

19 


24. /3-Fluoroethyl N-nitroso-N-methylcarbamate 

19, 30 

bp'® 

70-85° 

19 

13 

25. /3-Fluoroethyl N-(/3-chloroethyl)carbamate 

19, 30 

bp' 

105-108° 

19 


26. /3-Fluoroethyl N-nitroso-N-(/3-chloroethyl)carbamate 

19, 30 

bp2 

118-121° 

19 

13 

27. /3-Fluoroethyl glycine hydrochloride 

92j 

mp 

150.5° 

911 

911 

28. /3-Fluoroethyl betaine hydrochloride 

92j 

mp 

122° 

911 

911 

29. /3-Fluoroethyl nitrite 

19 


1.3589 

14 

13 




1.1427 

14 




bp380 

42-45° 

14 




bp760 

58-60° 

14 




voP® 

664 

14 


30. /3-Fluoroethyl thiocyanate 

92g 

bp'9 

77.5-78.5° 

92g 

91h 

31. /3-Fluoroethyl xanthate 

92g 

bp 

208-210° 

92g 

91h 

32. /3-Fluoroethyl chlorocarbonate 

19, 30 


1.3995 

14 

13 



bp750 

128° 

14 




voP® 

47.0 

14 



SECRET 


158 


METHYL FLUOROACETATE AND RELATED COMPOUNDS 


Table 1 {Continued). 


Compound 

Reference 

to 

synthesis 

Physical properties 
Property Reference 

Reference to 
toxicity 
data 

33. 6ts(j3-Fluoroethyl) carbonate 

19 


1.2939 

14 

13 



bp4 

71-72° 

14 




VOp5 

1.15 

14 


34. /3-Fluoroethyl chlorosulfonate 

19, 92g 

bp2« 

85-86° 

19 

13, 91f 

35. 5is(/3-Fluoroethyl) sulfate 

19, 92g 

no"" 

1.4177 

14 

13, 91f 




1.3678 

14 




bp2 

80-81° 

14 




voP® 

0.425 

14 


36. ins(/3-Fluoroethyl) arsenite 

19 

bp2-5 

132-134° 

19 

13 

37. tetrakis{0-F\uoroethy\) silicate 

19 

bpO.6 

102-104.5° 

19 

13 

38. <ns(j8-Fluoroethyl) borate 


bp 

192° 

91o 

91o 

39. /3-Fluoroethoxydichlorophosphine 

19, 31c 

bp^° 

50° 

31c 

13 



bp760 ' 

140-145° 

31c 


40. 5fs(/3-Fluoroethyl) hydrogen phosphite 

92n 

bpi-7 

109-110° 

92n 

91h 

41 . 5is(Diethylamino)-/3-fluoroethoxyphosphine 

19 

bp25 

108-111° 

19 

13 

42. Ethyl-5fs(/3-fluoroethoxy) phosphine 

19 

bpO.5 

40-49° 

19 

13 

43. <ns(/3-Fluoroethyl) phosphite 

19 

bpO.6 

100-105° 

19 

13 

44. 6rs(i8-Fluoroethyl) fluorophosphate 

92m 

bpO.5 

90-95° 

31b 

91f 

45. 6is(/3-Fluoroethyl)phosphoryl chloride 

19 

bpO.6 

108-112° 

19 


46. /3-Fluoroethylmercaptan 

33b 

bp225 

38-39° 

33a 

13 

47. 6ts(/3-Fluoroethyl) sulfide 

48 

Vp25b 

2.67 

48 

48 

48. /3-Chloroethyl /3-fluoroethyl sulfide 

19 


1.4872 

19 

13 




1.228 

19 




bp2o 

91.5° 

19 


49. jS-Fluoroethyl thiolacetate 

33b 

nD^° 

1.4538 

14 

13 




1.1451 

14 




bp30 

58-59° 

14 




voP® 

28.6 

14 


50. 1 ,2-6is( )3-Fluoroethylthio )ethane 

92h 

bp^"^ 

138-139° 

92h 

911 

5 1 . 7 -Fluoropropanol 

31d 

nv^^ 

1.3819 

31d 

20, 59c 



bp 

125-128° 

31d 


52. Epifluorohydrin 

19 


1.3696 

14 

13 




1.0967 

14 




bp763 

83.5-84° 

14 

. . • 



vop5 

260 

14 


53. Epifluorohydrin-phosphorus trichloride 

19 

bpi2 

72-74° 

19 

13 

54. l-Chloro-3-fluoropropanol-2 

19 


1.4290 

14 

13 




1.3014 

14 




bp®® 

75-76° 

14 

. . . 



voP® 

13.03 

14 


55 . 2-Chloro-3-fluoro- 1 -methoxy propane 

19 

bp750 

121-123° 

19 

20 

56. l-Fluoro-2-hydroxy-3-methoxypropane 

19 

bp®® 

70° 

19 

13 

57. l-Dimethylamino-2-hydroxy-3-fluoropropane 

58. 3-Fluoro-2-hydroxypropane-l-sulfonic acid, sodium 

19 

bp®® 

82-83° 

19 

13 

salt 

19 




20 

59. /3-Fluoro-/3 '-methoxy isopropyl chlorosulfinate 

19 

bp22 

93-96° 

19 

13 

60. 7-Fluoro-/3-hydroxypropyl propyl sulfide 

19 

bp22 

105-107° 

19 

13 

61. 6fs(/3-Fluoroethyl)amine 

94 

bp’®^ 

123-126° 

94 

91p 

62. 5is(j3-Fluoroethyl)methylamine 


bp762 

123-124° 

91p 

91p 

63. jS-Fluoroethyltrimethylammonium bromide 

92i 

mp 

244° 

92i 

911 

64. /3-Fluoroethyltriethylammonium bromide 

92i 

mp 

237° 

92i 

91h 

65. N-/3-Fluoroethylpyridinium bromide 

92i 

mp 

180° 

92i 

91h 

66. Fluoroacetaldehyde 

921 

bp 

89-92° 

91o 

91o, 921 

67. Fluoroacetaldehyde 2,4-dinitrophenylhydrazone 


mp 

147° 

91o 

91o 

68. Fluoroacetodiazomethane 

19 

bpi® 

41-44° 

19 

13 

69. co-Fluoroacetophenone 

19 


1.5309 

14 

13 




1.1747 

14 




mp 

22.8° 

14 




bp® 

79-80° 

14 




voP® 

0.591 

14 


70. Fluoroacetic acid 

’ 92 b 

mp 

31° 

92b 

91c 

71. Sodium fluoroacetate 

19, 22, 92e 



20 


SECRET 


INTRODUCTION 


159 


Table. 1 {Continued). 



Reference 




Reference to 


to 


Physical properties 

toxicity 

Compound 

synthesis 

Property 

Reference 

data 

72^ Aluminum fluoroacetate 

56 


.... 


59d 

73. Cupric fluoroacetate 

56 

. . . 

.... 

. . . 

59d 

74, Mercuric fluoroacetate 

56 

• . . 

.... 

• . • 

59d 

75, Thallous fluoroacetate 

56 

. . • 

.... 

• • . 

59d 

76. Triethyllead fluoroacetate 

92f 

mp 

180.5° 

92f 

91h 

77. Methyl fluoroacetate 

19, 92a 


1.3679 

14 

13, 20, 91c 

* 

. . . 


1.0593 

14 

• • • 


. . . 

mp 

35° 

14 

• . • 


• • • 

bp752 

103-103.5° 

14 

• • « 



vol^s 

119 

14 

• . • 

78. Ethyl fluoroacetate 

19, 92e 


1.3759 

14, 24q 

13, 91c 




1.0826 

14, 24q 

• • • 


. . . 

bp750 

114-118° 

14, 24q 

. . . 


• . . 

vops 

68.57 

14, 24q 

• . • 

79. Ethyl dichlorofluoroacetate 

47b 

bp730 

131.5-132° 

47b 

13 

80. /3-Fluoroethyl fluoroacetate 

19, 92d 


1.3802 

14, 19 

13, 91d 

• . . 

bp« 

85° 

14, 19 

• . • 


• • • 

VOp5 

7.81 

14, 19 


81. /3-Chloroethyl fluoroacetate 

19, 92d 


1.3160 

14 

13, 91c 

. . . 

bp23 

86° 

14 

• . . 


. • . 

vops 

3.55 

14 

• . . 

82. Allyl fluoroacetate 

19, 921 

nD^° 

1.4063 

14 

13, 911 


• • * 


1.0961 

14 

• • • 


• • • 

bp^° 

64.5-65° 

14 

• . • 


• • • 

VOp5 

31.69 

14 


83. Propyl fluoroacetate 

92e 

bp 

135-137° 

92e 

91c 

84. Isopropyl fluoroacetate 

19, 92e 


1.3804 

14 

13, 91c 



1.033 

14 

• . • 


• • • 

bp752 

121-123° 

14 

• . • 


• • • 

VOp5 

62.31 

14 

. . • 

85. j8-Ethylhexyl fluoroacetate 

. • • 


.... 

• . . 

59a, 59c 

86. Phenyl fluoroacetate 

19 

mp 

61.5-63° 

19 

13 

87. p-Chlorophenyl fluoroacetate 

19 

mp 

52-54° 

19 

13 

88. Cholesteryl fluoroacetate 

92f 

mp 

144-144.5° 

92f 

91h 

89. Methylene-6zs( monofluoroacet ate ) 

921 

mp 

57° 

921 

921 

90. Glycol 6ts(monofluoroacetate) 

91. Fluoroacetylcholine chloride 

92f 

bpi7 

140-141° 

92f 

13, 91h 

92. Fluoroacetylsalicylic acid# 

19^ 92j 

mp 

141-144° 

19, 92f 

13, 91h 


. . . 

mp 

131.6° 

. . . 

. . . 

93. S-/3-chloroethyl fluorothiolacetate 

19, 92j 

bpio 

80-81° 

19 

13, 911 

94. Phenyl fluorothiolacetate 

92f 

mp 

36.5-37.5° 

92f 

91h 

• . . 

bp^* 

132° 

92f 

. . . 

95. Methyl fluoroselenolacetate 

11 

nD-« 

1.4879 

14 

13 


• . • 


1.573 

14 

. . . 


• • • 

bp742 

130-132° 

14 

• • • 



VOp5 

69.95 

14 

. . • 

96. Fluoroacetyl fluoride 

19, 92e 

bp760 

35-40° 

19, 92e 

13, 91f 

97. Fluoroacetyl chloride 

19, 92b 


1.3831 

14 - 

13, 91c 




1.3530 

14 

• . • 



bp750 

69-71° 

14 



. • • 

voPs 

607 

14 


98. Fluoroacetonitrile 

19, 92g 


1.3324 

14 

13 


• . . 

bp752 

78° 

14 

. . • 


• . . 

voP® 

260 

14 

. . . 

99. Fluoroacetyl isothiocyanate 

19 


1.5327 

14 

13 




1.3527 

14 



• « . 

bp®° 

76° 

14 



• • • 

VOp5 

15.51 

14 

• . . 

100. Fluoroacetic anhydride 

92e 

bpi2 

88-89.5° 

92e 

91c 

101. Fluoroacetamide 

19, 92b 

mp 

108° 

19, 92b 

91c 

102. N-Methylfluoroacetamide 

92b 

mp 

64° 

92b 


103, N -Ni troso-N -methylfluoroacetamide 

92e 

bp^^ 

84° 

92e 

91c 


SECRET 


160 METHYL FLUOROACETATE AND RELATED COMPOUNDS 


Table 1 {Continued). 


Reference 


Reference to 


to 

Physical properties 

toxicity 

Compound 

synthesis 

Property Reference 

data 


104. N-j8-Chloroethylfluoroacetamide 

19, 92e 

mp 

65° 

19, 92e 

13 



bpO.3 

77° 

19, 92e 


105. N -/3-Hy droxyethylfluoroacetamide 

92e 

mp 

ca. 21° 

92e 




bpo-^ 

114° 

92e 


106. N,N-Diethylfluoroacetamide 

19 

bp^2 

86° 

19 

13 

107. N,N-6zs(/3-Chloroethyl)fluoroacetamide 

92e 

mp 

64.5° 

31a, 92e 




bp0.04 

102° 

31a, 92e 


108. a-Fluoroacetanilide 

23 

mp 

73-74° 

23 

20 

109. Fluoroacetylglycine ethyl ester 

92f 

mp 

50-50.5° 

92f 

91h 

110. Fluoromethylfluoroacetylurea 

921 

mp 

84° 

921 

921 

111. 2-Fluoroethane-l-sulfonyl chloride 

92g 

bp^^ 

81.5-84.5° 

92g 

91h 

112. Methyl a-fluoropropionate 

92e 

bp 

106.5-108.5° 

92e 

91f 

113. Ethyl /3-fluoropropionate 

19 

bp®® 

65-68° 

19 

20 

114. Diethyl fluoromalonate 

91c 

bpi® 

84-86° 

91c 

91c 

115. Sodium 7-fluorobutyrate 

19 


.... 


13 

116. Methyl 7-fluorobutyrate 

10, 19 


1.3887 

10 

13 




1.0662 

10 




bpioo 

79° 

10 




voF® 

39.6 

10 


117. Methyl a-fluoroisobutyrate 

92e 

bp 

108-109° 

92e 

91c 

118. Ethyl a-fluorobutyrate 

47b 

bp^® 

62.5-64° 

47b 

13 

119. Ethyl 7-fluorobutyrate 

47b 

bp^® 

68-70° 

47b 

13 

120. jS-Fluoroethyl 7-fluorobutyrate 

10, 19 

nD^° 

1.3953 

10 

13 



d2o 

1.604 

10 




bp7 

69° 

10 



. . . 

bp2® 

90° 

10 




voF® 

4.02 

10 


121. /3-Chloroethyl 7-fluorobutyrate 

10, 19 

nD^“ 

1.4278 

10 

13 



d2o 

1.2007 

10 




bpi 

61° 

10 




bp® 

80° 

10 




voF® 

1.18 

10 


122. Isopropyl 7-fluorobutyrate 

10, 19 

no^® 

1.396 

10 

13 



bpi®® 

93° 

10 




voP® 

20 

10 


123. Sodium 7-fluorocrotonate 

19 




20 

124. Methyl 7-fluorocrotonate 

10, 19 


1.4208 ^ 

10 

13 


bp®® 

70-73° 

10 




bp®® 

74° 

10 




voP® 

15 

10 


125. Methyl /3-chloro-7-fluorobutyrate 

10, 19 

no^® 

1.4227 

10 

13 



d2o 

1.2365 

10 




bp^® 

67-70° 

10 




bp"*® 

92° 

10 




voP® 

6.94 

10 


126. Sodium 7-fluoro-/3-hydroxybutyrate 

19 




20 

127. Methyl 7-fluoro-/3-hydroxybutyrate 

10, 19 


1.4184 

10 

13 



bpi® 

90° 

10 




bpi4 

94° 

10 




voP® 

1.15 

10 


128. jS-Chloroethyl 7-fluoro-/3-hydroxybutyrate 

19 

no^® 

1.4502 

19 

20 



bp®'* 

100-105° 

19 


129. Methyl 7-fluoro-/3-methoxybutyrate 

19 

bp*® 

55° 

19 

59b 

130. 7-Fluorobutyronitrile 

19 

d2® 

1.0034 

14 

13 



bp*®® 

98° 

14 




voP® 

12.89 

14 


131, 7-Fluorocrotonitrile 

19 

bp*® 

79-81° 

19 

13 

1 32 . 7-Fluoro-/3-hy droxybu ty ronitrile 

19 

710^2 

1.4232 

19 

59c 



bp® 

111-114° 

19 


133. 7-Fluorobutyrylcholine chloride 

19 

(Hygroscopic solid) 

19 

13 


SECRET 


INTRODUCTION 


161 


Table 

1 {Continued). 





Reference 




Reference to 


to 


Physical properties 

toxicity 

Compound 

synthesis 

Property 

Reference 

data 

134. Methyl 7 -fluorothiolbutyrate 

10, 19 


1.4587 

10 

13 



d 2 o 

1.1135 

10 




bp® 

54° 

10 




V 0 I-® 

8.44 

10 


135. Methyl 7 -fluoro-/ 3 -hydroxythiolbutyrate 

19 

riD^" 

1.4872 

19 

20 



bpO -2 

68-71° 

19 


136. Methyl a, 7 -difiuoroacetoacetate 

92e 

bp28 

113-115° 

92e 

91c 

137. Dimethyl a,a'-difluorosuccinate 

19 

bp®-^ 

68-70° 

19 

13 

138. Ethyl S-fluoro valerate 

91r 

bp^® 

54-58° 

91r 

91r 

139. Ethyl e-fluorocaproate 

92k 

bpi4 

82-84° 

92k 

92k 

140. /3-Fluoroethyl e-fluorocaproate 

92k 


103-105° 

92k 

92k 

141. Ethyl co-fluorocaprate 

91r 

bpi® 

134-136° 

91r 

91r 

142. Ethyl co-fluorohendecanoate 

91r 

bp ®-2 

82-84° 

91r 

91r 

143. sym-Tetrafluordinitroethane 





13 

144. 1-Chloro-l ,2,2-trifluorodimtroethane 



1.6595 

52 

13, 52 



bp76® 

98°( decomposes) 

52 




bp226 

61-62° 

52 




voP® 

382 

52 


145. Ethyl Q:,a,j3,/3-tetrafluoroethyl ether 





13 

146. a,a,|8,|8-tetrafluoroethyl-/3-hydroxyethyl ether 

147. Cyclohexyl a,a,/3,/3-tetrafluoroethyl ether 





13 





13 

148. Dodecyl a,a,j8,/3-tetrafluoroethyl ether 

149. Difluoroacetic acid 

47a 

bp76® 

134.2 

102 

13 



bp 2 ® 

67-70° 

102 


150. Methyl difluoroacetate 

19 

bp 

72-78° 

14 

13 


voP® 

361 

14 


151. Difluoroacetonitrile (trimeric) 

152. Bromotrifluoromethane 

46b 




13 

153. Trifluoroiodomethane 

46b 




13 

154. /3,/3,/3-Trifluoroethylamine 





13 

1 55 . /3,/3, jS-Trifluoroisopropylami ne 





13 

156. Dimethylthallium salt of hexoyltrifluoroacetone 

46a 




13 

157. Thallous trifluoroacetate 

158. Diethylthallium trifluoroacetate 

4 




13 

159. Methyl trifluoroacetate 

19 

bp 

42.5-43° 

19 

13 

160. Trifluoroacetyl chloride 

19 

bp76® 

9-11° 

19 

13 

161. Trifluoroacetonitrile 





13 

162. Thallous m-trifluoromethylbenzoate 

26b 




13 

163. m-Trifluoromethylphenyldichlorarsine 

26a 




13 


with an excess of sodium hydroxide in dry methanol. 
The resulting salt is collected, washed with methanol, 
dried, and screened. The required ethyl fluoroacetate 
is prepared in yields as high as 75 per cent from com- 
mercially available ethyl chloroacetate by a proce- 
dure closely resembling that described above for 
methyl fluoroacetate. Based on the average pilot 
plant yield, the intermediates required for the pro- 
duction of 100 lb of sodium fluoroacetate are: ethyl 
chloracetate, 250 lb; potassium fluoride, 214 lb; 
sodium hydroxide, 57 lb; methanol, 380 lb. 

3. ^-Fluoroethanol la.^eb, 90,92c prepared on 

a large laboratory scale (50 lb) by heating anhydrous 
potassium fluoride with ethylene chlorohydrin at 
180 C for 4 to 5 hours. Yields of 53 per cent are ob- 
tained. Except for the difference in temperature the 
reaction is carried out as described for methyl fluoro- 


acetate. During the heating ethylene oxide is formed 
almost quantitatively from the ethylene chlorohydrin 
but appears to be the product of a reversible side re- 
action. Attempts to produce j8-fluoroethanol from 
ethylene oxide and hydrogen fluoride have been un- 
successful. 

/3-Fluoroethanol is a colorless liquid with a pleasant 
alcohol-like odor. It boils at 102.5 C at atmospheric 
pressure and is completely miscible with water. 
Several of its physical properties have been deter- 
mined. 

4. Methyl y-fluorohutyrate is prepared by 
treating trimethylenechlorobromide with sodium 
cyanide to produce a mixture of 7-chloro and7-bromo- 
butyronit riles. The mixture is then heated under 
pressure with anhydrous potassium fluoride at 200 C 
to give 7-fluorobutyronitrile, which is converted to 


SECRET 


162 


METHYL FLUOROACETATE AND RELATED COMPOUNDS 


the corresponding methyl ester by treatment with 
methanol and acid. The overall yield of methyl 
7 -fliiorobutyrate obtained in preparations on a large 
laboratory scale has been about 25 per cent for the 
three-step process. 

5. Methyl y-fluoro-^-hydroxyhutyrate, methyl /3- 
chloro-y-fluorobutyrate, and methyl y-fluorocroto- 
nate are prepared as follows. Epichlorohydrin 
when heated under pressure at 225 C with potassium 
fluoride is converted into epifluorohydrin. Treatment 
of the latter with anhydrous hydrogen cyanide and a 
small amount of sodium cyanide gives y-fluoro-iS- 
hydroxybutyronitrile in excellent yield. This inter- 
mediate is converted to methyl y-fluoro-jS-hydroxy- 
butyrate by treatment with methanol and acid. 
Methyl jS-chloro-y-fluorobutyrate is produced by the 
action of thionyl chloride and pyridine on the hy- 
droxy compound. Methyl y-fluorocrotonate may 
then be formed by dehydrohalogenation of the /5- 
chloro compound with triethylamine. Yields are good 
except in the case of the first step involving the con- 
version of epichlorohydrin to epifluorohydrin. It has 
not yet been possible to raise the yield of this step 
above 40 per cent, although 70 to 74 per cent of the 
unconverted epichlorohydrin is recovered in a form 
suitable for re-use. The overall yield based on the 
amount of epichlorohydrin utilized is 46 per cent for 
methyl 7-fluoro-/(3-hydroxybutyrate, 39 per cent for 
methyl /S-chloro-y-fluorobutyrate, and 33 per cent 
for methyl y-fluorocrotonate. All three esters are 
stable colorless liquids. 

An alternative method not requiring high-pressure 
equipment has been developed for the preparation of 
methyl y-fluorocrotonate on a laboratory scale. 
Methyl y-bromocrotonate, prepared by bromination 
of methyl crotonate with N-bromosuccinimide, is re- 
fluxed at atmospheric pressure with anhydrous po- 
tassium fluoride. The product is slowly distilled from 
the mixture as the reaction proceeds. Yields of ap- 
proximately 40 per cent are obtained. 

In addition to the synthetic procedures already 
described, a variety of methods has been used to pre- 
pare other fluorinated aliphatic compounds. Men- 
tion may be made of the preparation of difluoro- and 
trifluoroacetic acids by the oxidation of 1,1-dichloro- 
3,3-difluoropropene and l,l,2-trichloro-3,3,3-triflu- 
oropropene, respectively ^ (see Chapter 40) ; the 
preparation of several ethers of a;,Q:,(3,/3-tetrafluoro- 
ethanol by the addition of alcohol to tetrafluoro- 
ethylene; the synthesis of |8-fluoroethyl thiolacetate, 
from which /3-fluoroethylmercaptan may be obtained 


by hydrolysis, by the peroxide-catalyzed addition 
of thiolacetic acid to vinyl fluoride ; the synthesis 
of tetrafluoro- 1,2-dinit roe thane and chlorotrifluoro- 
1,2-dinitroethane by the addition of nitrogen tetrox- 
ide to the corresponding halogenated olefines; and 
the synthesis of derivatives of €-fluorocaproic acid 
from cyclohexanone through e-hydroxycaproic acid 
and the corresponding bromo-compound, which is 
treated with silver fluoride.®^*" 

10.2.2 Chemical Properties 

Methyl fluoroacetate has been the subject of most 
of the work on the chemistry of the aliphatic fluorine 
compounds considered in this chapter. It is readily 
hydrolyzed to fluoroacetic acid and methyl alcohol, 
the half life of the ester in water buffered at pH 7 
being less than 1 hour.^^ On the other hand, the flu- 
orine atom can be removed from the molecule only 
by relatively drastic treatment. No reagent has been 
found which will bring about rapid replacement at 
room temperatures. As an example, no fluoride ion 
is produced by heating methyl fluoroacetate for 
5 minutes with 20 per cent alcoholic potassium hy- 
droxide, although more prolonged heating (18 hours 
on steam bath) does result in the incomplete libera- 
tion of fluoride ion.®^'^ Concentrated acids at steam 
bath temperatures hydrolyze the fluorine atom at 
unspecified rates.®® Under physiological conditions of 
pH and temperature, no fluoride ion is liberated in 
72-96 hours in the presence of any of a variety of ni- 
trogen bases, sulfur compounds, and inorganic salts. 

A further example of the chemical inertness of the 
fluorine atom in fluoroacetates is given by the follow- 
ing comparison of the rates of replacement of halogen 
by sulfite in the ethyl esters of fluoroacetic, chloro- 
acetic, and bromoacetic acids : 



Temp 

Bimolecular 

Compound 

C 

velocity constant 

Ethyl bromoacetate 

25 

18.3 

Ethyl chloroacetate 

25 

0.13 

Ethyl fluoroacetate 

45 

4.5 X 10-5 


Limited data on the storage stabilities ^ of both 


^ A recent report from the Chemical Warfare Service 
(TCIR 345, Surveillance of Fluorine Compounds, September 5, 
i945) testifies to the stability of methyl fluoroacetate and re- 
lated compounds with respect to pressure development as 
follows: (1) methyl fluoroacetate and /3-fluoroethanol are 
stable in 75-mm steel shell with respect to pressure for at 
least 1 year at 65 C; (2) methyl y-fluorobutyrate does not de- 
velop pressure in 6 months at 65 C when in contact with a 
steel strip in glass apparatus; and (3) methyl 7-fluoro- 
jS-hydroxybutyrate develops a pressure of about 120 psi at 
35 per cent void in glass apparatus at 65 C in either the pres- 
ence or absence of a steel strip. 


SECRET 


CHEMICAL STRUCTURE IN RELATION TO TOXICITY 


163 


methyl fluoroacetate and sodium fluoroacetate also 
illustrate the high stability of these compounds. 
]Methyl fluoroacetate undergoes no visible change on 
storage for 8 months at 60 C in glass containers in the 
presence of varnished steel, but a slight deposit of 
silica forms in the presence of bare steel. Sodium 
fluoroacetate undergoes no visible change, loses no 
weight, and does not alter in fluoride content on 
storage for 30 days at 65 C in tin-plated cans ; the tin 
surfaces show no change.^^® 

Methyl fluoroacetate resists oxidation by aqueous 
permanganate or chromate. In the presence of 
chromic acid plus concentrated sulfuric acid, pro- 
duction of hydrogen fluoride occurs, slowly in the 
cold and rapidly on heating.*® 

Methyl fluoroacetate exhibits a thiosulfate de- 
mand on heating at 100 

There is no evidence that other members of this 
series differ strikingly from methyl fluoroacetate in 
the stability of the fluorine atom, or that they exhibit 
peculiarities in the reactions of the more common 
functional groups. 

10.2.3 Detection and Analysis 

The fluorine atom in compounds of the fluoro- 
acetate type is too stable toward hydrolysis to make 
practical the use of this reaction for purposes of 


identification. Therefore, recourse is had to oxidative 
or thermal decomposition producing hydrogen flu- 
oride, which is then detected by its etching effect on 
glass or by its ability to bleach metallic lakes of ap- 
propriate dyes.^^’^^’*®’*^’®®*^ A device making use of 
the etching effect to produce a nonwettable surface 
in small glass tubes has been examined by the Brit- 
ish, si, 82 . 83 platinum filaments and hot platinized 

silica gel both decompose volatile fluorine compounds 
and both have been utilized in experimental appar- 
atus designed for field use.^^’^^ 

Satisfactory tests for fluoroacetate ion in water 
have been developed.'*® 

All quantitative methods for determination of 
fluorine in compounds of the fluoroacetate type have 
involved the conversion of the organically bound 
fluorine to fluoride ion, which is then determined by 
one of the standard methods. 

The detection and analysis of aliphatic fluorine 
compounds are reviewed in more detail in Chap- 
ters 34 and 37. 

10.3 CHEMICAL STRUCTURE IN 

RELATION TO TOXICITY 24* ^^ ®*^-* *'^ ®^® 

In Table 2 are listed representative compounds 
which do and do not possess to a marked degree the 


Table 2. Aliphatic fluorine compounds illustrating the relationships between molecular structure and toxicity. 


Compounds exhibiting definite fluoro- 
acetate- or 7 -fluorobutyrate-like 
toxicity* 

Reference 


Compounds exhibiting no or only 
slight fluoroacetate- or 7 -fluoro- 
butyrate-like toxicity* 

Reference 

Fluoroacetic acid 

91c, 92e 

Acids 

Difluoroacetic acid 

13 

Sodium fluoroacetate 

13, 20, 34a 

Salts 

Sodium chloroacetate 

13, 38c 

Sodium 7 -fluorobutyrate 

13 


Sodium bromoacetate 

13, 38c 

Sodium 7 -fluoro-| 8 -hydroxybutyrate 

24g 


Sodium iodoacetate 

13, 38c 

Sodium 7 -fluorocrotonate 

24t 


Thallous trifluoroacetate 

13 

Methyl fluoroacetate 

Esters of halogenated acids 

See Table 3 Methyl fluoroformate 

13 

Ethyl fluoroacetate 

13, 91c 


Ethyl fluoroformate 

91c 

Propyl fluoroacetate 

91c 


Methyl chloroacetate 

91c 

Isopropyl fluoroacetate 

13, 91c 


Ethyl dichlorofluoroacetate 

13 

Allyl fluoroacetate 
/3-Chloroethyl fluoroacetate 
/3-Fluoroethyl fluoroacetate 
/3-Chloroethyl fluorothiolacetate 

Methyl fluoroselenolacetate 

13 

See Table 4 
See Table 4 
13 

13 


Methyl a-fluoropropionate 

91f 

Methyl 7 -fluorobutyrate 

See Table 4 


Ethyl /3-fluoropropionate 

20 

Ethyl 7 -fluorobutyrate 

13 


Methyl a-fluoroisobutyrate 

91c, 92e 

Isopropyl 7 -fluorobutyrate 

13 


Ethyl a-fluorobutyrate 

13 

/3-Chloroethyl 7 -fluorobutyrate 

See Table 4 


Ethyl 5-fluorovalerate 

91r 

/3-Fluoroethyl 7 -fluorobutyrate 

See Table 4 


Ethyl oj-fluorohendecanoate 

91r 

Methyl 7 -fluorothiolbutyrate 

Methyl / 3 -chloro- 7 -fluorobutyrate 

Methyl 7 -fluoro-/ 3 -hydroxybutyrate 

See Table 4 
See Table 4 
See Table 4 





SECRET 


164 METHYL FLUOROACETATE AND RELATED COMPOUNDS 


Table 2 {Continued). 

Compounds exhibiting definite fluoro- 


Compounds exhibiting no or only slight 


acetate- or 7 -fluorobiityrate-like 


fluoroacetate- or 7 -fluorobutyrate- 


toxicity* 

Reference 

like toxicity* 

Reference 

Methyl 7 -fliioro-/ 3 -hydroxythiolbutyrate 

See Table 4 



Methyl 7 -fluorocrotonate 

See Table 4 

Diethyl fluoromalonate 

91c 

Ethyl e-fluorocaproate 

91o 



/3-Fluoroethyl e-fluorocaproate 

91r 



Ethyl oi-fluorocaprate 

91r 




A nhydrides 



Fluoroacetic anhydride 

91c, 95e 




Nitriles 





Fluoroacetonitrilef 

13, 91c 



7 -Fluorobutyronitrilet 

13 



7 -Fluorocrotonitrile f 

13 



T rifluoroacetonitrile 

13 


Aldehydes 



Fluoroacetaldehyde 

91o 




Amides 



Fluoroacetamide 

91b, 92b 



N-i3-chloroethyl fluoroacetamide 

13 



N-nitroso-N-methyl fluoroacetamide 

91c 




Acid halides 



Fluoroacetyl chloride 

13, 91c 

Acetyl fluoride 

13 

Fluoroacetyl fluoride 

•13, 91f 

Chloroacetyl fluoride 

13, 91c 



Butyryl fluoride 

13 



Crotonyl fluoride 

13 


Alcohols 

* 


/3-Fluoroethanol 

See Table 4 

7 -Fluoropropanol 

59b 


Esters of Fluor oethanol 



mono{ ^-Fl uoroethyl ) derivatives 


/3-Fluoroethyl chloroformate 

13 



/3-Fluoroethyl acetate 

91f 



/3-Fluoroethyl fluoroacetate 

See Table 4 



/3-Fluoroethyl chloroacetate 

91c, 92g 



/3-Fluoroethyl nitrite 

13 



Dichloro(/3-fluoroethoxy)phosphine 

13 



/3-Fluoroethyl sulphuryl chloride 

91f 




his{ 0-Fl uoroethyl) derivatives 


6ts(/3-Fluoroethyl) carbonate 

13 

6 fs( /3-Fluoroethyl) fluorophosphate 

91f 

6 ts( /3-Fluoroethyl) chloromaleate 

13 



6 ts( /3-Fluoroethyl) sulfate 

13, 91f,92g 



Di-/3-fluoroethyl hydrogen phosphite 

91h 



Ethyl 6 fs(i 8 -fluoroethoxy)phosphine 

13 




tris{0-Fluoroethyl) derivatives 


tris{ /3-Fluoroethyl ) orthof ormate 

13 



/rfs(/3-Fluoroethyl) phosphite 

13 



1 

Ethers and acetals 


/3-Fluoroethyl methyl ether 

91f 

a,Q:,/3,/3“Tetrafluoroethyl /3 '-hydroxy- 


/3-Fluoroethyl chloromethyl ether 

13 

ethyl ether 

13 

/3-Fluoroethyl /3-chloroethyl ether 

13 



/3-Fluoroethyl phenyl ether 

91h 



hts(/3-h4uoroethoxy)methane 

13 




Miscellaneous 



his{ /3-Fluoroethyl )amine 

91p 

N-methy l- 6 ?s( /3-fluoroethyl )amine t 

91p 

a-Fluoroacetylsalicylic acid 

13, 91h 

l-Chloro-2-fluoroethanet 

13, 91f 

Fluoroacetyl glycine, ethyl ester 

91h, 92f 

/3-Chloroethyl /3-fluoroethyl sulfide 

13 

Glycol di(monofluoro)acetate 

91h, 92f 

T rifluoroiodomethane 

13 



Fluoroethyl thiocyanate 

91 h, 92g 



Fluoroethane sulphonyl chloride 

91h, 92g 



/3-Fluoroethyl triethyl ammonium bromide 

91h, 92i 



1 ,2-6fs(i8-Fluoroethylthio) ethane 

911 


* A compound possessing fluoroacetate-like or T-fluorobutyrate-like toxicity would, for any species at doses equal to or slightly greater than those listed 
for methyl fluoroacetate or methyl "y-fluorobutyrate in Tables 3 and 4, produce the characteristic symptoms after the usual latent period (see below), and 
at least some deaths within 2 days. 

t May possess slight activity, but markedly less than corresponding esters. 
t Produce methyl fluoroacetate symptoms but only at somewhat higher concentrations. 


SECRET 


TOXICOLOGY 


165 


Table 3. Toxicity of methyl fluoroacetate. 

With the exception of the entries marked with an asterisk, the figures are approximations based on 

limited numbers of observations. 


Species 

LC 50 (mg/l) 
t — 10 min 

Reference 

Intra- 

venous 

LD 50 (mg/kg) 
Reference Subcutaneous 

Reference 

Oral 

Refer- 

ence 

Dog 

0.025* 

24t 

0.08 

24t 

0. 1-0.2 

73 

0.1-0.2 

73 

Cat 

(0.025-0.05)1 

24i 

0.2* 

40b 

0.3 

73 

0.3 

73 

Rabbit 

0.065* 

24t 

0.33* 

24t 

0.3-0.5 

24i, 73 

0.5 

73 

Guinea pig 

0.15 

24d, 91c 



0.2 

73 

0.5 

73 

Goat 

0.2 

76 

<2.0 

51 

1.0 

73 

1.0 

73 

Rat 

0.3 

24d, 73, 76 



2.5 

73 

3.5 

73 

Mouse 

3.2* 

24f,t 

17* 

24t 

5-20 

24i, 73 

(5-6) 

24j, 73 

Rhesus monkey 

0.8-2.0 

73, 76 

5-15 

51 

10-12 

73 

10-12 

73 

Cercopithecus monkey 





>50t 

91q 



Frog 





100-200 

40a 




t Estimate based on susceptibility to /3-fluoroethanol. 
t Intraperitoneal injection. 


characteristic toxicological properties of methyl 
fluoroacetate and methyl y-fluorobutyrate. Com- 
pounds which produce the characteristic toxicological 
actions fall into the following categories: 

1 . The following acids, in some cases tested only 
as salts and esters: fluoroacetic, y-fluorobutyric, 
y-fluoro-/3-hydroxybutyric, jS-chloro-y-fluorobutyric, 
y-fluorocrotonic, e-fluorocaproic, and co-fluorocapric. 

2. Other simple derivatives of the above acids and 
their thiol analogs, including anhydrides, amides, 
aldehydes, and acid halides, but not the nitriles. 

3. i3-Fluoroethanol, its esters, and certain other 
derivatives. 

The following compounds do not evoke the char- 
acteristic toxic effects: 

1 . Di- and poly-fluoro derivatives of the toxic 
mono-fluoro compounds. 

2 . Chlorine, bromine, and iodine analogs of the 
toxic fluorinated derivatives. 

3. Fluoride-liberating compounds such as acid 
fluorides. 

4. Derivatives of aliphatic acids in which the 
fluorine atom is not in the terminal position (i.e., 
methyl a-fluoropropionate, methyl a-fluoroisobutyr- 
ate, ethyl a-fluorobutyrate, and diethyl fluoromalon- 
ate). 

5. co-Fluoro derivatives of aliphatic acids with an 
odd number of carbon atoms (e.g., ethyl jS-fluoro- 
propionate, ethyl 5-fluorovalerate, and ethyl co-fluoro- 
hendecanoate) . 

Thus, the F-CH 2 -group appears to be essential. 
Its presence is not sufficient, however, and presum- 
ably it must form the end of a chain of an even num- 
ber of carbon atoms. It is also necessary that the 
proper group, usually an oxygenated one, form the 


other end of the chain (e.g., methyl fluoroacetate is 
highly toxic, l-chloro-2-fluoroethane is less so, and 
fluoroacetonitrile is relatively non toxic). That other 
features of the molecules play a role in determining 
the degree of toxicity by inhalation is also revealed 
by the large differences which exist between the pre- 
cisely determined LC bo’s for a number of related de- 
rivatives containing one and twoF • CH 2 -groups, 241 . 8.44 
and by the large differences in toxicity which are 
associated with various /S-substitutions in methyl 
7 -fluorobutyrate (see Table 4). 

10.4 TOXICOLOGY 

10.4.1 Toxicity for Animals 

The toxicity of methyl fluoroacetate for animals is 
set forth in Table 3 and may be evaluated in com- 
parison with hydrogen cyanide, the LD bo of which 
is in the order of 1 mg/kg for most species, including 
man (see Chapter 2). It is noteworthy that: (1) the 
species variation is unusually large — the dog is ap- 
proximately 100 times more susceptible than the 
mouse or monkey and two tested species of monkeys 
show considerably different susceptibilities; and 
(2) the compound is approximately as toxic when 
administered by mouth as when injected intrave- 
nously or subcutaneously. 

The toxicity of jS-fluoroethanol for various species 
is comparable to that of methyl fluoroacetate ; jS-flu- 
oroethyl fluoroacetate, the most toxic member of the 
fluoroacetate group, is somewhat more potent 
(Table 4). Methyl 7 -fluorobutyrate and related com- 
pounds (Tables 2 and 4) produce toxic effects similar 
in a general way to those of methyl fluoroacetate but 
exhibit less pronounced species variation, principally 


SECRET 


166 


METHYL FLUOROACETATE AND RELATED COMPOUNDS 


Table 4. Inhalation toxicities of fluorinated aliphatic compounds. 

With the exception of the mouse LCso’s, the figures are approximations based on limited data. 


LC 50 (mg/ 1 , nominal, for < = 10 min) 


Compound 

Monkey 

(Rhesus) 

Mouse 

Rat 

Guinea 

pig 

Rabbit 

Cat 

Dog 

Methyl fiuoroacetate 

0.8-2.073>76 

3.22«.t 

Q 324d,73,76 

0.1524d.91c 

0.06524t 


0.02524t 

jS-Chloroethyl fiuoroacetate 


Q 7 -|-24d,91c 

0.2 ± 

0.15+24d.91c 

0 . 121 ® 



/ 3 -Fluoroethyl fiuoroacetate 


0.6324g 

0.2 ± 94d 

0.0724d.91d 

0.052id 



/ 3 -Fluoroethanol 

1 524d,e 

1.2241 

0.2-l-24d.76 

0.1524d.91c 

0.02524d 

0.03524d 

(0.007)24d 

Methyl 7 -fiuorobutyrate 

0 . 524^1 

0.12241 

0.35 ±24h 

0.0724h 

0.03524h 

0.03524h 

0.05241* 

Methyl 7 -fiuorothiolbutyr- 

ate 


0.064241 


.... 




/3-Chloroethyl 7 -fiuorobutyr- 

ate 

> 0 . 32 b 

0.05424j 


0.1±24j 


.... 


/ 3 -Fluoroethyl 7 -fiuorobutyr- 

ate 

0.5 4-2 

0.077241 

0.224h 

0.035241* 

<0.07524h 

0.02524h 

0.025241* 

Methyl jS-chloro-y-fiuorobu- 

tyrate 


0.16241 






Methyl 7 -fiuoro-| 8 -hydroxy- 

butyrate 

0 . 22 ^p 

0.02324“ 


.... 

<0.06324P 

0.124-’ 

<0.06324-’ 

Methyl 7 -fiuoro-/ 3 -methoxy- 

butyrate 


> 0.159b 


>0.159b 




Methyl 7 -fiuoro-/ 3 -hydroxy- 

thiolbutyrate 

0.224P 

<0.0324P 



<0.06324-’ 


0.06324-’ 

/3-Chloroethyl 7 -fiuoro-| 8 -hy- 

droxybutyrate 


0.04824s 






Methyl 7 -fiuorocrotonate 

<0.524h 

0.089241 


0.1524h 





because of a much greater toxicity for mice. When 
tested on monkeys, the members of this group are 
more toxic than methyl fiuoroacetate but not so 
toxic as either mustard gas or phosgene. 

Methyl fiuoroacetate, and presumably also the 
7-fluorobutyrate derivatives, are detoxified in the 
body, but only at a slow 

Changes in L(C 0 50 with changes in exposure time 
over the range 1 to 100 minutes have been observed 
in experiments with methyl fiuoroacetate, /S-fluoro- 
ethyl fiuoroacetate, and jS-fluoroethanol, but the 
effects are not large.^^'^’®’'^^’’^® The L{Ct)^Q of methyl 
7-fluorobutyrate for mice is the same for exposures 
of 1, 10, and 100 minutes,^^® and that of methyl 7-flu- 
orocrotonate may not be significantly different for 
exposures of 10 or 100 minutes or for two fractional 
exposures at a 24 -hour interval.^^* Summation of the 
effects of multiple sublethal doses of methyl fluoro- 
acetate administered at daily intervals by mouth, 
injection, or gassing has been observed but some de- 
toxification occurs and, with sufficiently small incre- 
ments, the equivalent of several lethal doses can be 
tolerated.^^®’’^^’®^^ However, species differences appear 
to exist; successive small doses produce a more pro- 
nounced cumulative effect in guinea pigs than rats, 
the latter species probably developing an increased 
resistance to the poison. Indeed, recent data dem- 


onstrate that a small dose (approximately 0.1 LHso) 
administered orally or subcutaneously confers a sta- 
tistically significant degree of resistance upon rats 
tested 24 hours later with an administered 

orally or intramuscularly.^^® A similar phenomenon 
has been reported for orally administered sodium 
fiuoroacetate, but it would not appear that the ele- 
vation of resistance is sufficient to affect the value of 
the salt as a rodenticide. 

A characteristic latency is associated with the 
visible effects of poisoning by methyl fiuoroacetate 
and related compounds. Even 10 to 20 times the 
lethal dose produces symptoms only after a minimum 
delay of 15 minutes. Survival times of animals dy- 
ing as a result of inhalation of median lethal dosages 
are almost always at least 1 hour, usually 2 to 12 
hours, less frequently 12 to 24 hours, and rarely 
longer.^^*^’®^® The derivatives of 7-fluorobutyric acid 
act similarly to the fluoroacetates but the latent 
period may be somewhat briefer and the recov- 
ery of sublethally poisoned animals more pro- 
tracted. 

There are two immediate causes of death in methyl 
fiuoroacetate poisoning: action on the heart, culmi- 
nating in ventricular fibrillation and circulatory 
failure; and stimulation of the central nervous sys- 
tem, producing convulsions, apnea, and death with- 


SECRET 


TOXICOLOGY 


167 


out severe cardiac ® abnormalities.®^ The relative 
severity of the two effects is not the same in different 
species: the cardiac action is the primary cause of 
death in monkeys, goats, and rabbits; effects on the 
central nervous system predominate in rats, cats, 
and dogs.'^®’®^’®^^’'^® Transient but sublethal central 
nervous effects occur in some species (e.g.. Rhesus) 
which eventually die with ventricular fibrillation, 
and cardiac effects in other species (e.g., the cat) 
which die of respiratory failure following severe con- 
vulsions.®^ The poisoned heart has a decreased ex- 
citability and the effects are not due to diminished 
coronary blood flow.®^ 

In experiments on three monkeys methyl 7-fluoro- 
butyrate produced cardiac depression and arrhyth- 
mias, as well as marked parasympathetic symptoms, 
but ventricular fibrillation has not been observed.®®^ 
jS-Fluoroethyl 7-fluorobutyrate, likewise tested on 
only three monkeys, produced effects similar to those 
of methyl fluoroacetate but was more toxic. ®^^ Both 
compounds produced effects similar to methyl fluoro- 
acetate in the cat and rabbit.®®^ 

The symptoms associated with poisoning by 
methyl fluoroacetate and related compounds have 
been described in detail for various species 24d.g,h.j,q, 
51 ,58k, 73 , 91a interpreted as resulting from 

the actions of the poisons on the heart or nervous 
system, or both. 

Pathological studies 24a,d,h,73,9ik,q animals dying 
acutely from single doses reveal no significant 
changes other than signs referable to venous con- 
gestion. In animals exposed repeatedly to sublethal 
doses until death ensues,®^*" there are found the 
sequelae of protracted venous congestion attributable 
to heart failure, definite abnormalities in the myo- 
cardium, changes in the kidney which may or may 
not be secondary to disturbances in the metabolism 
of other organs, and changes of doubtful significance 
in some other organs; no unequivocal pathological 
changes have been observed in the nervous system. 

10.4.2 Physiological Mechanism 

A number of clinical pathological and biochemical 
studies have been made to throw light on the cellular 
mechanism of action of methyl fluoroacetate and re- 
lated compounds. 

® It may be noted that the conclusions concerning cardiac 
effects have been based on detailed, continuous electro- 
cardiographic observations, and that species which exhibit 
central nervous stimulation concomitantly develop abnormal 
electroencephalograms in the absence of notable cardiac 
irregularities.®^*’ 


m,n,q,93,98 Thcir heterogcneous character precludes a 
review of all the isolated facts which eventually may 
prove to be of significance. 

The evidence is strong that methyl fluoroacetate 
does not owe its toxicity to the liberation of fluoride 
ion at critical loci in the body. In accord with chemi- 
cal studies on the stability of the fluorine atom (see 
Section 10.2.3), none of a large number of biochemi- 
cally important substances, including some with a 
high reactivity toward organic halogens, liberates 
fluoride from methyl fluoroacetate at physiological 
conditions of pH and temperature; nor is fluoride 
ion liberated when the ester is incubated with rat 
tissues.^® Moreover, methyl fluoroacetate does not 
show a marked tendency to inactivate enzymes 
which are highly susceptible to fluoride. 

It has been proposed as a working hypothesis that 
all the toxicologically active compounds under con- 
sideration may be the precursors of some common 
toxic material, possibly the fluoroacetate ion, which 
could be produced, for example, by hydrolysis of 
esters, oxidation of /S-fluoroethanol, and jS-oxidation 
of the 7-fluorobutyrates.®^' Although this hypothesis, 
which conceivably could explain the facts set forth 
in Section 10.3, “Chemical Structure in Relation to 
Toxicity,” has not as yet been submitted to sys- 
tematic test, the following findings may be cited as 
bearing upon it. 

1. Sodium fluoroacetate, fluoroacetic acid, and 
fluoroacetamide possess approximately the same 
toxicity as methyl fluoroacetate and produce symp- 
toms after a comparable latency.®^ The latency 
in poisoning by the ester is not, therefore, determined 
by time for hydrolysis. However, this does not imply 
that hydrolysis of the ester may not be a necessary 
prelude to the initiation of toxic action. Tissues and 
blood contain a methyl fluoroacetate esterase, 
which in the rat is sufficiently active to afford the 
ester a half life of not more than a few minutes — a 
fraction of the usual latent period for symptoms.^* 

2. That the characteristic effects of methyl fluoro- 
acetate and sodium fluoroacetate on the myocardium 
do not require in vivo chemical changes in other organs 
is suggested by experiments on eviscerated rabbits ®^ 

Arginine, serine, histidine, tyrosine, proline, asparagine, 
glutamic acid, lysine, tryptophane, alanine, glycyl glycine, 
imidazole, guanidine, cysteine, glutathione, S-allyl thiourea, 
/3-mercaptoethanol, 2,3-dimercaptopropanol, carbobenzoxy 
methionine, thiodiglycol, benzylamine, triethanolamine, tetra- 
ethanolammonium chloride, hexamethylenetetramine, and 
/3-aminobenzoic acid; or sodium thiosulfate, sodium sulfide, 
sodium bisulfite, or sodium iodide. 


SECRET 


168 


METHYL FLUOROACETATE AND RELATED COMPOUNDS 


and proved by tests with isolated, perfused hearts of 
the cat,^^ rabbit,®^*" and guinea pig,®^*' and with the 
isolated papillary muscle of the cat.^^ A similar con- 
clusion with respect to effects on the central nervous 
system is suggested by the finding that local appli- 
cation of methyl fluoroacetate to one cerebral hemi- 
sphere produced convulsive discharges after the usual 
latency for symptoms ; although the convulsions were 
generalized, the effect of the poison on the treated 
hemisphere appeared to be greater than on the con- 
tralateral areas. 

3. On the contrary, it may be necessary for jS-flu- 
oroethanol to undergo chemical change, possibly by 
oxidation to fluoroacetate in the liver. This is sug- 
gested by the finding that the alcohol exerted no 
effect on the isolated, perfused heart when tested at 
concentrations at which methyl fluoroacetate pro- 
duced marked decreases in rate and survival time.®^"" 

4. If the toxicity of the 7 -fluoro butyrates and 
other longer-chained fluorinated aliphatic acids de- 
pends on the production of fluoroacetate by /3-oxida- 
tion, their relatively high toxicity for some species 
(Table 2 ) would require that they be concentrated 
to a greater degree than the fluoroacetates at critical 
loci in the body. That the /3-oxidation of 7 -fluoro- 
butyrate is not prerequisite for all its actions upon 
biological systems is indicated by evidence that 
methyl 7 -fluorobutyrate is not converted to fluoro- 
acetate by rabbit kidney cortex in vitro, in spite of 
the fact that both compounds markedly inhibit the 
oxidation of acetate by this prepara tion.^®* Substitu- 
tions on the j3-carbon atom are, however, important 
determinants of inhalation toxicity, as is revealed by 
the widely differing toxicities of a number of the 
butyric acid derivatives listed in Table 4. 

Changes indicative of a derangement in carbo- 
hydrate metabolism in methyl fluoroacetate poison- 
ing in various mammalian species are increases in 
blood sugar, nonprotein nitrogen,^®^ inorganic 
phosphate,®*^ lactic acid,^®^’^*^-^ pyruvic acid,^®*^ and 
lactate-pyruvate ratio. In rabbits there is a marked 
reduction in liver glycogen and, in the heart, 
marked decreases in total acid-soluble phosphorus 
and organic soluble phosphorus. Serum potassium 
and calcium show only minor increases.^**" 

Negative results have been obtained in many but 
not all the studies on the effects of fluoroacetate on 
enzyme systems in vitro and on the metabolism of 
tissues obtained from poisoned animals or treated 
with the poison after 

Illuminating experiments have been performed 


with an isolated skeletal muscle, the sartorius of the 
frog, but have not been extended as yet to cardiac 
muscle.^* The resting oxygen consumption and 
the contractility of the unfatigued sartorius are not 
affected by the poison at a concentration of 0.005M, 
but the extra oxygen consumption following activity 
is strongly inhibited. The inhibition is associ- 
ated with a greatly decreased resynthesis of phos- 
phocreatine and abolition of the delayed heat 
production normally associated with aerobic re- 
covery of stimulated muscle.^®^ ® Similarly, the extra 
oxygen consumption produced by pretreatment of 
the isolated muscle with the stimulants caffeine and 
dinitrophenol is essentially abolished by fluoro- 
acetate. Similar changes are produced by sodium 
azide but the mechanism of action is different: azide 
inhibits cytochrome oxidase and adenyl pyrophos- 
phatase, whereas methyl fluoroacetate has no in- 
hibitory action either upon these enzymes or upon 
cytochrome reductase. 

The possibility that fluoroacetate inhibits lactic 
acid dehydrogenase is suggested by the findings that 
the isolated frog sartorius utilizes pyruvate (also 
acetate) but does not oxidize added lactate,^®*" and 
that the effects of fluoroacetate upon the isolated 
guinea pig heart are counteracted by pyruvic acid 
derivatives but not by sodium lactate. An in vitro 
study on lactic acid dehydrogenase likewise revealed 
an inhibition of the enzyme prepared from yeast, 
although in another experiment the enzyme pre- 
pared from heart muscle was not reported to be in- 
hibited by methyl fluoroacetate.^®*" Data relating to 
the production of lactate by the stimulated poisoned 
muscle under anaerobic conditions are not con- 
sistent. In the case of rabbit kidney cortex prepa- 
rations in vitro, however, methyl fluoroacetate in- 
hibits the oxidation of glucose and certain intermedi- 
ates of carbohydrate metabolism but it has no effect 
on the anaerobic phase of carbohydrate degradation 
resulting in the formation of lactic acid. The latter 
findings have led to the suggestion that a locus of 
action may be at one of the steps in the dehydro- 
genation of pyruvate via the citric acid cycle. 

The effect of fluoroacetate on the oxygen con- 
sumption of stimulated skeletal muscle has been 
found to be reversible,^® offering some hope that 
methyl fluoroacetate poisoning may eventually be 
subject to treatment. Moreover, if the oxygen con- 
sumption of heart muscle should prove to be as 
easily inhibited by methyl fluoroacetate as that of 
stimulated skeletal muscle, the possibility would 


SECRET 


TOXICOLOGY 


169 


exist that a therapeutic agent could be found in a 
carbohydrate intermediate the oxidation of which is 
not strongly inhibited d* 

The slight therapeutic value of procaine and p- 
aminobenzoic acid in fluoroacetate-poisoned monkeys 
and the absence of a corresponding effect with other 
antifibrillatory drugs (see below) suggested the al- 
ternative possibilities that p-aminobenzoic acid 
might be fluoroacetylated, thereby detoxifying the 
poison, or that the toxicity of the fluoroacetate might 
be associated with an inhibitory action on normally 
occurring acetylations. However, experiments reveal 
that the monkey does not acetylate, and therefore 
probably does not fluoroacetylate, p-aminobenzoic 
acid,®*^ that the acetylation of p-aminohippuric acid 
by rabbits is not markedly affected in fluoroacetate 
poisoning, and that fluoroacetate does not inhibit 
the acetylation by liver slices of sulfanilamide, p- 
aminobenzoic acid, or choline. On the other hand, 
fluoroacetate does produce some inhibition of the 
utilization of acetate in vitro by rabbit heart and 
kidney preparations and by rat kidney, liver, and 
heart slices.^®'" In the case of Corynebacterium crea- 
tinovorax and of yeast, the inhibition is almost com- 
plete.®®^ These and other findings have led to the sug- 
gestion that fluoroacetate may produce a profound 
alteration in the metabolism of carbohydrate by vir- 
tue of a specific inhibitory effect on the oxidation of 
acetate.®®® However, poisoned caffeine-stimulated 
muscle does utilize acetate.^®® 

The resting potential of frog peripheral nerve is 
sensitive to concentrations of methyl fluoroacetate 
as low as O.OOIM.®^® ^^ The potential was reduced in 
poisoned nerves by a period of anoxia, and the oxi- 
dative recovery was little affected by addition of 
acetate or acetyl phosphate, but was counteracted 
by addition of pyruvate. 

10.4.3 Therapy 

No satisfactory procedures for the treatment of 
fluoroacetate poisoning have been discovered. Tests 
have been made of substances and procedures de- 
signed to prevent convulsions, to stimulate respira- 
tion, to stimulate diuresis and excretion of the poison, 
to prevent ventricular fibrillation and otherwise re- 
store the failing heart, to promote detoxification by 
fluoroacetylation, to compete for enzyme systems 
with fluoroacetate, and to supply necessary metabo- 
lites the formation of which may be cut off by the 
action of the poison on enzyme systems. 

58c,e,i,j ,k,l,73,91g,j ,m 


Intracardiac injections of procaine accompanied by 
artificial respiration and cardiac massage through the 
thoracic wall temporarily restore an organized beat 
to the monkey heart fibrillating as a result of methyl 
fluoroacetate poisoning; but fibrillation recurs and 
eventually proves fatal in spite of continued treat- 
ments and the presence of subcutaneous deposits 
of procaine.®^ ’®®‘^ 

Administration of large doses of sodium p-amino- 
benzoate to anesthetized monkeys {Rhesus and Ateles) 
poisoned with one LDioo dose of methyl fluoroacetate 
corrects the cardiac disturbances and saves the ma- 
jority of animals. ®®‘’^ However, the value of this 
treatment is limited inasmuch as it does not save 
monkeys poisoned with larger doses ®®j or rabbits 
poisoned with four LD ^q’s; nor does it combat 
the lethal action of methyl fluoroacetate in the rat, 
a species which dies of central nervous rather than 
cardiac effects.®®*" 

Large concentrations of sodium acetate (0.1 per 
cent) prolong the survival of the isolated rabbit 
heart perfused with depressant concentrations of 
methyl fluoroacetate, but the acetate ion has exerted 
little or no protection when administered to the 
poisoned animal.®®* Similarly, the sodium salt and 
other derivatives of pyruvic acid protect the isolated 
guinea pig heart poisoned with methyl fluoroacetate 
but have little or no therapeutic value in vivo.^^^ 

Various anesthetics have been shown to be effec- 
tive in controlling the convulsions associated with 
methyl fluoroacetate poisoning,^^®’®*'^*® ^ but even 
when combined with respiratory stimulants they do 
not decrease the mortality.®^® Sodium pentabarbital 
is contraindicated because it increases the mor- 
tality. 

The following additional substances and proce- 
dures have been without significant value under the 
tested conditions in saving the lives of animals poi- 
soned with methyl fluoroacetate or j8-fluoroethanol : 
artificial respiration; artificial respiration plus 
sodium phenobarbital; 2'*^ '^® oxygen plus carbon di- 
oxide; ^® urethane, paraldehyde, or chloral hydrate, 
with or without theophylline or coramine; the- 
ophylline; ®®®’®*^ bromide;®^® Dilantin (sodium di- 
phenyl hydantoin) ; ^®-***« morphine hydrochloride; 
quinidine, digitalis, quinidine-digitalis, or caffeine;®®® 
papaverine ; ®®j yohimbine; ®®* anticholinesterase drugs 
or aconite;®®® atropine; ^'*®'®®® ephedrine; ®®®’® thia- 
mine;®®® glucose; 2^*® potassium salts; ®®®’®i'" calcium 
salts;**'*®’®®® barium salts;®®® 2,3-dimercaptopropanol 
(BAL), acetophenone, or cobalt acetate.®**" 


SECRET 


170 


METHYL FLUOROACETATE AND RELATED COMPOUNDS 


10.4.4 Toxicity for Man 

Man is among the species which are relatively re- 
sistant to methyl fluoroacetate. Direct evidence 
comes from the results of ingestion of the compound 
by a British volunteer. Upon taking an oral dose 
of 0.4 mg/kg in water he experienced no symptoms 
other than a slight, possibly psychogenic, feeling of 
unsteadiness upon standing up 13 ^ hours after the 
dose was taken. Similar ingestion of 0.65 mg/kg pro- 
duced no symptoms other than a feeling of unsteadi- 
ness for a few minutes 1 hour after the dose and a 
slight malaise 5 hours later; however, the subject 
continued work in the laboratory with no obvious 
loss of efficiency and his electrocardiogram and elec- 
troencephalogram, recorded at frequent intervals, 
showed no deviation from the normal. It is to be 
noted that the dose ingested was greater than the 
LD^q for guinea pigs, rabbits, cats, and dogs. 

Various lines of evidence suggested that the 
lethal dose per os is in the order of 6-8 mg/kg. Ex- 
posure of workers for prolonged periods to low con- 
centrations of the vapor produced marked weak- 
ness, reluctance for any physical effort, and strong 
mental depression with periods of nervous irritation 
difficult to control, followed by physical and mental 
exhaustion, drowsiness, and giddiness; a few days’ 
rest resulted in marked improvement.® 

Assuming (1) that the above estimate of the lethal 
dose per os for man is correct, (2) that the toxicity of 
methyl fluoroacetate is more or less independent of 
the route or rate of administration, and (3) that 
100 per cent absorption of inhaled vapor occurs, one 
may calculate that the lethal vapor dosage for a 
70-kg man breathing 10 1pm (relative inactivity) 
would be 50,000 mg min/m^, corresponding to a 
10-minute LC^o of 5 mg/1; for a man breathing 40 
1pm, corresponding to exercise intermediate between 
a walk at 5 mph and a slow run,^ the figure would be 
12,500 mg min/m^, the equivalent of 1.25 mg/1 for 
10 minutes. Although the validity of this method of 
calculation has been questioned,^® it has been shown 
to yield good approximations when applied to the 
dog and rabbit, the only larger species for which 
both the LCbo’s and LDbo’s have been determined 
with precision.^^* For defensive purposes the British 
have estimated the L{Ct)bo at 4,000 and 7,000 mg 
min/m®.'^® '^® For most species the margin between 
the convulsive and lethal doses is small. 

® These symptoms, experienced by Polish chemists, 
prompted the initial toxicological examination of the effects 
of methyl fluoroacetate on animals. 


The mild, indistinctive odors of methyl fluoro- 
acetate and jS-fluoroethanol make it possible that 
large vapor dosages could be inhaled undetected. It 
has been reported that methyl fluoroacetate at 
0.05 mg/1 is just detectable, that at 0.2-0. 3 mg/1 it 
would easily be overlooked, and that at 0.4 mg/1 it 
possesses a fruity smell and may produce a slight 
feeling of tightness in the chest. Most of the 
7 -fluorobutyrates are probably somewhat more odor- 
ous than methyl fluoroacetate but it has been empha- 
sized that methyl 7-fluoro-i3-hydroxybutyrate pos- 
sesses only a very slight odor, similar to but much 
fainter than that of ethyl lactate.^^^ 

A prominent symptom in severe poisoning is the 
occurrence of repeated and severe convulsions indis- 
tinguishable from status epilepticus; less dramatic 
symptoms may include nausea, vomiting, dizziness, 
and fall in body temperature. In addition to the 
symptoms, tests with urine may aid in the recog- 
nition of fluoroacetate poisoning, for a toxic, fluorine- 
containing substance not present in normal urine is 
excreted. The fluorine may be converted to 

fluoride and detected by chemical test or the 
urine given to rats by stomach tube, the character- 
istic symptoms of fluoroacetate poisoning then 
being produced. 

In the absence of specific therapeutic procedures 
for fluoroacetate poisoning, cases can at present only 
be treated symptomatically. Morphine has been 
recommended to allay distress, anxiety, and con- 
vulsions, but barbiturates (i.e., pentobarbital so- 
dium) are contraindicated.®^® 

10.5 EVALUATION AS WAR GASES 

Evaluation of the potentialities of methyl fluoro- 
acetate and related compounds in terms of available 
data and present concepts of chemical warfare indi- 
cates that none of the derivatives possesses the gen- 
eral utility of currently standardized gases. They 
remain a subject of some military concern, however, 
in view of their potential use as food and water 
poisons (see Section 10.6) or for other special pur- 
poses. 

For man methyl fluoroacetate is not appreciably 
more toxic, and in all probability is considerably less 
toxic, than currently standardized gases. The lethal 
vapor dosage, calculated above on the basis of the 
demonstrated low oral toxicity to be in the order of 
12,000 mg min/m® for ventilation rates correspond- 
ing to moderate physical activity and several times 


SECRET 


EFFECTIVENESS AS FOOD AND WATER POISONS 


171 


this value for men at rest, may be compared with the 
minimum dosages of standard agents currently 
recommended as adequate for the following tasks: 


Task 

To produce a large propor- 
tion of deaths or severe 
casualties in surprise at- 
tacks with nonpersistent 
gases (dosages to be ob- 
tained within 2 minutes) 
To produce skin burns of 
sufficient severity to to- 
tally disable 50 per cent 
of masked troops not 
equipped with protective 
clothing (dosages to be 
obtained witliin 4 hours) 
To produce eye damage of 
sufficient severity to 
cause temporary blind- 
ness among troops not 
wearing gas masks 


Dosage 

Agent (mg min/m^) 
Phosgene 3,200 

Hydrogen 

cyanide 5,000 

Cyanogen 

chloride 11,000 

Mustard 

vapor 1,000 (T > 80 F) 
2,000-4,000 
(T = 60-80 F) 


Mustard 

vapor 200 


In view of the relatively low toxicity for man, it is 
apparent from a consideration of the physical proper- 
ties of methyl fluoroacetate (Table 5), the most 
volatile stable compound of the group, ^ that it would 


Table 5. Physical properties of methyl fluoroacetate and 
of currently standardized nonpersistent agents. 


Property 

Methyl 

fluoro- 

acetate 

Hydro- 

gen 

cyanide 

Cyano- 

gen 

chloride 

Phosgene 

Liquid density 

(g/ml at 25 C) 

1.17 

0.68 

1.2 

1.36 

Boiling point, C 

104 

26 

12.6 

8.3 

Freezing point, C 

-35 

-13.4 

-7 

-104 

Latent heat of evap- 

oration, cal/g 

100 

210 

135 

60 

Vapor pressure, 
mm Hg 

at 25 C 

20 

740 

1,200 

1,400 

at -20 C 


88 

180 

230 

Volatility, mg/1 

at 25 C 

119 

1,060 



at -20 C 


145 

680 

1,460 


be more difficult than in the case of the standard 
nonpersistent gases to achieve in the field vapor 
dosages sufficiently large to be lethal in surprise at- 
tacks; and, in view of the effectiveness of the can- 
ister,*® the breaking of the gas mask cannot be con- 
sidered a feasible task. 

The volatilities of jS-fluoroethanol and of various 
stable fluoroacetate derivatives having toxicities 

^ The more volatile /3-fluoroethyl nitrite, fluoroacetyl fluo- 
ride, and fluoroacetyl chloride are chemically unstable. 


comparable to methyl fluoroacetate range from that 
of methyl fluoroacetate (i.e., 119 mg/1 at 25 C) down 
to very low values. Thus, agents of any desired de- 
gree of persistence are potentially available. Al- 
though the indistinctive odor and relative difficulty 
of detection by chemical means would confer upon 
these compounds a certain insidiousness, their lack 
of effectiveness on the eyes and skin renders them 
inferior in general utility as persistent agents to such 
vesicants as mustard gas and ^m(i8-chloroethyl)- 
amine (HNS). Except in drinking water, their decon- 
tamination offers no special problems.*® 

Methyl fluoroacetate possesses excellent storage 
stability (see Section 10.2.2) and its explosion sta- 
bility is believed to be sufficient to permit its dis- 
persal from chemical munitions now in use.^^j It is 
potentially available in quantity. 

There are no data bearing upon the toxicity for 
man of the derivatives of y-fluorobutyric acid. On 
the basis of the comparative toxicities of these de- 
rivatives and of methyl fluoroacetate for the monkey 
(Table 4), they would be suspected of being some- 
what more toxic for man than is methyl fluoroacetate. 
They are, however, less volatile (Table 1) and nota- 
bly more difficult to manufacture. 

10.6 POTENTIAL EFFECTIVENESS AS 
FOOD AND WATER POISONS IN 
WARFARE^^’^^®'®’^*'^®’*^ 

The chemical and toxicological properties of 
methyl fluoroacetate and related compounds make 
them potential water and food poisons. They are 
approximately as toxic when administered orally as 
when injected or inhaled; to a degree they may act 
as cumulative poisons; and they are not readily de- 
tected by smell or taste. Although methyl fluoro- 
acetate itself undergoes hydrolysis, the resulting 
fluoroacetic acid is stable and toxic. 

At concentrations of 0.1 per cent or less in water, 
methyl fluoroacetate has no smell or taste; *® 34 1 of 
a 0.1 per cent solution would probably be lethal for 
man (see Section 10.4.4). This concentration in milk 
is readily accepted by rats and dogs,*^ although it is 
not freely accepted in otherwise pure drinking water 
by rats, nor are jS-fluoroethanol and sodium fluoro- 
acetate at 0.01 per cent (100 parts per million) freely 
accepted by mice.^^®-® The effectiveness of sodium 
fluoroacetate as a rodent bait poison is discussed 
below. 

Filtration of contaminated water with charcoal 


SECRET 


172 


METHYL FLUOROACETATE AND RELATED COMPOUNDS 


removes methyl fluoroacetate but not the hydrolytic 
product, fluoroacetic acid.*® Filtration with charcoal 
plus pyridine is said to remove not only methyl flu- 
oroacetate but also, from neutral solution, sodium 
fluoroacetate as well.'^'* The detection of fluorine com- 
pounds in contaminated water is discussed in 
Chapter 34. 

10.7 USE AS RODENTICIDES 

Sodium fluoroacetate was one of several substances 
studied in the chemical warfare program in the 
United Kingdom and the United States which were 
recommended by Division 9 of NDRC to thq Fish 
and Wildlife Service of the Department of Interior 
for test as rodenticides.'^^ Preliminary tests with 
small samples (200 lb) submitted by Division 9 were 
so successful that the division subsequently pre- 
pared an additional 1,000 lb 22 for large-scale field 
trials. Field campaigns in a number of states and in 
military establishments in this country and abroad 
were conducted by the Fish and Wildlife Service, by 
the Typhus Control Unit of the Public Health 
Service, and by the medical departments of the 
Army and Navy. The results demonstrate that 
sodium fluoroacetate, coded 1080, is one of the most 
promising available rodenticides.'‘®‘^’®°“'^° 

Sodium fluoroacetate possesses the following re- 
quirements of a good rodenticide: high toxicity and 
acceptability, stability, lack of volatility, lack of irri- 
tation and toxic properties for human skin, lack of 
inflammability, and potential availability in quan- 
tity at reasonable cost.^®^ The oral lethal doses for 


various species of rats and other rodents of concern 
in public health and agriculture range between 0.1 
and 5 mg/kg.'‘^^’^°® The substance is effective in baits 
at much lower concentrations than in the case of 
other rodenticides. Excellent results have been ob- 
tained in field trials utilizing 6 oz of sodium fluoro- 
acetate per 250 lb of cereal or ground meat bait.^^^ 
Water solutions are also highly effective. A concen- 
tration of 1/2670 has been recommended for general 
use,'^® although concentrations ten times greater 
(i.e., 5 oz gal) are sufficiently acceptable to rats and 
have been used with good results.'^^^ 

As in the case of other rodenticides, the possibility 
of accidental human poisoning cannot be ignored, 
particularly in the absence of effective methods for 
treatment of fluoroacetate poisoning. However, it 
would appear that concentrations sufficiently low to 
make accidental human poisoning improbable may 
still be effective in rodent control. The human lethal 
dose is believed to be of the order of 5-10 mg/kg 
(see Section 10.4.4). On the other hand, the oral 
lethal doses for cats and dogs are very low (0.1 to 
0.5 mg/kg) and, therefore, the likelihood of acci- 
dental poisoning of these species confers a certain 
disadvantage upon sodium fluoroacetate. 

The sodium salts of 7-fluorobutyric, 7-fluoro-i3-hy- 
droxybutyric, and 7-fluorocrotonic acids are several 
times as toxic for rats as is sodium fluoroacetate. 
However, in view of the already high toxicity of the 
latter, this apparent disadvantage is more than offset 
by the greater difficulty and expense of their prepa- 
ration. 


SECRET 


Chapter 11 


CADMIUM, SELENIUM, AND THE CARBONYLS OF IRON 

AND NICKEL 

By John A . Zapp 


11.1 INTRODUCTION 

I N THE SEARCH for new chemical warfare agents, 
the toxic properties of certain metals were not 
neglected. The increasing use of cadmium in indus- 
try, for example, had revealed that the inhalation of 
finely divided cadmium metal, the oxide, or salts was 
capable of producing severe lung edema comparable 
with that produced by phosgene.®®'®* Selenium com- 
pounds showed similar properties,®® and, although 
somewhat less toxic than cadmium on an absolute 
basis, they produced physiological effects much more 
promptly. Being inorganic, these agents offered 
promise for inclusion in burning- type munitions or 
incendiaries as well as for dispersion by high-ex- 
plosive shell. The carbonyls of iron and nickel 
aroused considerable interest not only because of 
their inherent toxicity, but also because they break 
down catalytically in contact with gas mask carbon, 
yielding carbon monoxide which is not absorbed in 
the canister but passes into the mask.®^ *^ Thus the 
carbonyls might be valuable in attacking either 
masked or unmasked troops. Compounds of mercury, 
thallium, tin, antimony, lead, chromium, and ger- 
manium were screened by the University of Chicago 
Toxicity Laboratory [UCTL],^ but without reveal- 
ing any of special interest for chemical warfare 
purposes. 

The part of Division 9 of the National Defense 
Research Committee [NDRC] in the field of heavy 
metals was largely one of screening the toxicity of a 
great number of compounds, many of which were 
prepared under Office of Scientific Research and 
Development [OSRD] contracts. The detailed in- 
vestigation of the promising compounds, including 
investigations of cadmium and selenium and the 
carbonyls, was carried out by the Chemical Warfare 
Service and by the Directorate of Chemical Warfare 
in Canada. 

11.2 CADMIUM 

11.2.1 Physiological Action 

Cadmium, its oxide, and salts are toxic by any 
route of administration, but their particular signifi- 


cance in chemical warfare lies in the fact that finely 
divided dusts can be set up either by thermal com- 
bustion of incendiary mixtures containing cadmium 
or by the explosive dispersal of cadmium compounds. 
These dusts are quite toxic by inhalation,®®'®* pro- 
ducing lung edema comparable with that observed 
in phosgene poisoning. 

Exposure to high concentrations of cadmium 
causes some early respiratory irritation, which pro- 
gresses to marked dyspnea within a few hours. Two 
cats exposed to a high concentration of cadmium 
oxide fume for 30 minutes ®® showed on autopsy ex- 
tensive acute pulmonary injury with edema, injury 
to the bronchioles and alveolar ducts, and acute 
alveolar emphysema. Liver and kidney damage was 
also found. Exposure to lower concentrations of 
cadmium fumes or dust results in a temporary irri- 
tation of the respiratory tract which disappears 
shortly after cessation of exposure only to reappear 
within about 12 hours with increasing severity ac- 
companied by general malaise. Within about 24 to 
48 hours dyspnea is marked and cyanosis occurs 
prior to death.^®-^^-^*-®® On autopsy the lungs are 
found to be firm, but with interstitial and perivascu- 
lar edema and extensive hemorrhage. Liver and kid- 
ney show evidence of fatty infiltration. 

Several cases of human poisoning by inhalation of 
cadmium have been reported. In one of these, re- 
ported in 1858,®® three men were exposed to cadmium 
carbonate dust. Symptoms did not occur until sev- 
eral hours after exposure and then consisted of 
dyspnea, dizziness, vomiting, and diarrhea. One 
patient apparently contracted pneumonia by second- 
ary infection, but all three recovered eventually. 
Fifteen cases of human cadmiurA poisoning from in- 
halation of cadmium oxide fumes, two of which were 
fatal, have been reported from Canada.®^ In all these 
cases, dyspnea, which did not become severe until 
several hours after exposure, was the most prominent 
symptom, although the majority of cases also ex- 
hibited gastrointestinal symptoms. The two men 
who died showed congestion of the lungs, pulmonary 
edema, hemorrhage into the lungs, atelectatic areas, 
proliferative interstitial pneumonitis, and catarrhal 


SECRET 


173 


174 


CADMIUM, SELENIUM, AND CARBONYLS OF IRON AND NICKEL 


bronchitis. Liver and kidney damage was also 
present. 

11.2.2 Toxicology 

The toxicity of cadmium oxide by inhalation is 
summarized in Table 1 for various species and ex- 


Table 1. Toxicity of cadmium oxide by inhalation. 


Species 

UCtho 
(mg min/1) 

Exposure 

time 

(min) 

Reference 

Mouse 

0.5 

15-30 

60 


0.87 

10 

17 


0.58 

10 

15 


0.34 

10 

7 

Rat 

2.0 

2 

40 


1.1 

5 

40 


0.78 

10 

40 


0.9 

30 

40 


1.3-1.8 

5-10 

46 

Guinea pig 

3.0 

15-30 

60 

Rabbit 

3.0 

15-30 

60 


>1.8 

5-10 

46 


<5.2 

10 

18 

Goat 

<1.6 

5-10 

46 

Dog 

3.0 

10 

45 

Monkey 

15-20 

10 

45 


15 ± 

15 

45 


21 + 

30 

45 

Man 

1.5-2.9 

75-90 

49 


posure times. Some of the variability in results is un- 
doubtedly due to variation in particle size of the 
cadmium oxide. When dispersed from most incendi- 
ary munitions the median particle size is usually less 
than 1.0 M in diameter, but agglomeration of particles 
frequently takes place. This point has been particu- 
larly emphasized in the estimate of the L(C0 5 o for 
man,^^ in which the elementary particles were less 
than 0.3 in diameter, but in which the cloud actu- 
ally consisted of large numbers of small agglomerates 
of 1.0 to 2.0 M in diameter, with a small number of 
agglomerates 40 n or greater in diameter. The L{Ct)^Q 
of 2.9 mg min/1 was based on analytical C^’s ob- 
tained in an experiment set up to duplicate condi- 
tions which resulted in two cases of fatal cadmium 
oxide poisoning in an industrial plant. There ap- 
peared to be every reason to believe that the concen- 
tration of cadmium oxide in the original accident 
was not greater than that obtained in the duplicate 
experiment, but the L(C 05 o’s for rats and rabbits 
exposed in the duplicate experiment were about 
twice those previously obtained with arc-produced 
cadmium oxide fumes. The difference was attributed 
to the greater median particle size in the duplicate 
experiment and led to the hypothesis that the L{Ct)^Q 
for man might be as low as 1.5 mg min/1 under con- 


ditions where particles do not agglomerate.^^ It is 
worth noting that prior to the Canadian experi- 
ments there was a tendency to assume that the 
toxicity of cadmium oxide for man would closely re- 
semble that for the monkey, making the human 
L(Ct) 5 o of the order of 15 mg min/1. This estimate 
would seem to be entirely too high. The true toxicity 
of cadmium oxide for man may be as great or greater 
than that of phosgene (see Chapter 3). 

The toxicity of cadmium metal itself and of cad- 
mium compounds other than the oxide by inhalation 
was tested at the UCTL. The results are shown in 
Table 2. So far as mice are concerned, there is con- 

Table 2. Inhalation toxicities of cadmium compounds 
for mice.^ 

A = analytical concentration; N = nominal 
concentration. 


Compound 

Ct (as Ct 

compound) (as Cd) 
(mg min/1) (mg min/1) 

Avg. 

particle 

diameter 

(m) 

Mortality 

Cadmium 

0.38 A 

0.38 

<0.2 

18/20 

Cadmium 

0.17 A 

0.17 

<0.2 

18/19 

Cd oxide 

0.34 A 

0.30 

<0.2 

L{Ct),o 

Cd chloride 

2.3 A 

1.4 

<0.5 

L{Ct)so 

Cd fluoride 

1.8 N 

1.2 

? 

0/20 

Cd fluoborate 

6.5 N 

1.9 

? 

8/20 

Cd fluosilicate 

6.7 N 

2.1 

? 

9/20 

Cd sulfide 

1.35 A 

1.05 

<0.3 

5/20 

Cd selenate 

2.27 N 

0.93 

? 

0/20 

Cd nitrate 

3.85 A 

1.4 

<0.5 

LiCtho 

Cd phosphate 

6.5 N 

3.67 

? 

2/20 


siderable variability in the toxicity of the different 
cadmium compounds even when dosages are calcu- 
lated in terms of the cadmium content of the com- 
pound. It is also of interest that cadmium metal 
itself is more toxic than any of its salts. In this in- 
stance, the combination of cadmium with anions 
which are themselves toxic resulted in decreased 
rather than enhanced toxicity. Unfortunately it is 
not possible from the data to assess the effect of 
particle size on the different estimates of the L{Ct) ^o’s 
but taking the results at their face value it would 
appear that cadmium oxide is the most toxic of the 
cadmium compounds. This fact is fortunate since 
the oxide is easily prepared in the field by the com- 
bustion of incendiary munitions containing cadmium 

metal.15’24, 29,46 

11.2.3 Assessment of Value as a 
Chemical Warfare Agent 
Cadmium appears to be a promising material for 
addition to incendiaries if toxicity as well as fire is 


SECRET 


SELENIUM 


175 


Table 3. Toxicity of selenium dioxide by inhalation. 


Species 

Ct 

(mg min/l) 

Exposure 

time 

(min) 

Mortality 

Time to 
death 
(hr) 

Reference 

Mouse 

2.30* 

10 

0/20 


7 

Rat 

2.30t 

10 

0/6 


7 

Rabbit 

5.89t 

20 

4/6 

6, 6.5, 40, 132 

27 


6.59t 

10 

4/6 

3.8, 11, 13, 32 

27 


13.18t 

20 

6/6 

2.8, 3, 3, 5, 5.5, 8 

27 

Goat 

5.89t 

20 

0/2 


27 


6.59t 

10 

2/2 

5.5, 84 

27 


8.83t 

30 

3/4 

6, 18, 130 

27 


13.18t 

20 

2/2 

4, 4.5 

27 


* SeOa dispersed by atomization of aqueous solution. 

t SeOj formed and dispersed by detonation of Se/high-explasive mixture. Peak range of particle size 0.6 to 1.0 m in diameter. 


desired. The cadmium oxide which results from the 
combustion of cadmium metal in incendiary mixes 
is odorless and probably not irritating enough in the 
presence of smoke and burning materiel to be de- 
tected by odor. 

Cadmium oxide smoke is brown in color, however, 
and may be detected by appearance after it has been 
used a few times. Cadmium chloride may also be dis- 
persed from burning munitions 18 , 19,22 lethal con- 
centrations may be obtained in mixtures which are 
indistinguishable in appearance from harmless 
screening smokes. Attempts have been made to dis- 
perse cadmium compounds by the explosion of mu- 
nitions containing cadmium or its compounds, 
50,55,64 method of dispersal is relatively in- 

efficient because of the rapid agglomeration and 
settling of the cadmium particles. 

One drawback to the use of cadmium in offensive 
warfare is the delay in appearance of toxic effects, 
since, as has been pointed out, dyspnea does not 
usually become severe until at least 12 hours after 
exposure. If, however, incendiary attacks are planned 
against industrial installations, large stores of ma- 
teriel, cities, and the like, such targets are usually 
well beyond the front lines and a delay in the appear- 
ance of toxic effects can be readily accepted. From 
the available data it would appear that cadmium 
might play a very important role if a military re- 
quirement for toxic incendiaries should arise. 

11.3 SELENIUM 

A review of the toxicity of selenium as a potential 
industrial hazard appeared in 1938.^® At that time it 
was known that selenium compounds were toxic 
when ingested and that hydrogen selenide was toxic 
on inhalation. On this basis it was predicted that 
soluble dusts such as .selenium oxides (Se02, SeOs, 


H 2 Se 03 , H 2 Se 04 ) and certain halogen compounds 
might be toxic because of the ease by which they 
could be absorbed from the lungs and gastrointestinal 
tract. These toxic dusts might be set up by the com- 
bustion of incendiary mixtures containing selenium 
or its compounds or by the detonation of explosives 
containing selenium. Hence selenium, like cadmium, 
was investigated as a possible chemical warfare 
agent. 

11.3.1 Physiological Action 

The action of selenium appears to be similar to 
that of cadmium, with the exception that the onset 
of toxic effects is more rapid after exposure to sele- 
nium. Goats and rabbits exposed for periods of 10 to 
30 minutes to selenium oxide smoke showed dyspnea 
and tachycardia on removal from the exposure 
chamber. Animals receiving a fatal dose usually died 
within 24 hours and sometimes within 3 hours. On 
autopsy, pronounced pleural effusion and pulmonary 
edema were found, plus hemorrhages in the lungs, 
heart, and kidneys, and marked congestion of the 
glomeruli and spleen.^^ 

11.3.2 Toxicology 

All workers agree that in absolute terms selenium 
is less toxic than cadmium. The toxicity of selenium 
oxide toward various species is shown in Table 3. 
Other selenium compounds were screened for toxicity 
at the UCTL without revealing any of greater in- 
terest or effectiveness than the oxide. 

11.3.3 Assessment of Value as a 
Chemical Warfare Agent 

Selenium oxide smoke differs from cadmium oxide 
smoke in the following respects: (1) it is less toxic 
than cadmium oxide; (2) it is acrid and irritating to 


SECRET 


176 


CADMIUM, SELENIUM, AND CARBONYLS OF IRON AND NICKEL 


the respiratory tract, whereas cadmium oxide is 
odorless and relatively nonirritating; (3) it is white, 
whereas cadmium oxide is brown; (4) it kills or dis- 
ables more quickly than cadmium oxide. In contrast 
to cadmium, which was found to be most effective in 
incendiarj^ munitions, selenium has been studied 
mainly in explosive-type munitions.^^-^^’^^’^'* 

Since selenium oxide is white, it would not be de- 
tected by appearance alone if used in conjunction 
with ordinary screening smokes. On the other hand, 
its irritant properties might well lead exposed troops 
to mask promptly. Whereas its relatively rapid 
action as compared with that of cadmium is a 
desirable feature, it is doubtful whether this out- 
weighs its lower absolute toxicity. The potential use- 
fulness of selenium oxide as a chemical warfare agent 
cannot be accurately assessed on the basis of avail- 
able information. If there is a future requirement for 
this type of agent, further experimentation, and par- 
ticularly field trials, are in order. 

11.4 NICKEL CARBONYL AND IRON 
CARBONYL 

Nickel carbonyl, Ni(CO) 4 , was discovered in 1890, 
and iron pentacarbonyl, Fe(CO) 5 , in 1891. Both com- 
pounds can be made to dissociate into carbon mon- 
oxide and the pure metal under controlled condi- 
tions, and this reaction forms the basis for the com- 
mercial preparation of pure nickel (Mond process), 
a method which is in use to the present day. Iron 
carbonyl was more difficult to prepare than nickel 
carbonyl, the yield being only about 1 per cent of 
theoretical, so that the Mond process was not eco- 
nomical for the preparation of iron on a large scale. 
In the 1920’s, however, iron carbonyl found some 
use in Europe as an “antiknock” for gasoline, and 
more recently it has been an important source of the 
pure, finely powdered iron which is used in powder 
metallurgy. 

The toxicity of the metal carbonyls was recog- 
nized as early as 1891 and was extensively investi- 
gated and reported in 1907-1908.’^® Chemical war- 
fare interest in the compounds arose primarily from 
two facts: (1) they are toxic enough to merit con- 
sideration as agents for use under certain circum- 
stances where they might not be readily detected, 
and (2) they dissociate readily in contact with the 
active carbon of the gas mask, releasing four or five 
volumes of carbon monoxide per mole of carbonyl. 
The carbon monoxide is not absorbed by the canister 


of the service gas mask. Therefore, the carbonyls 
provide an indirect way of bringing carbon monoxide 
into offensive chemical warfare. 

11.4.1 Physiological Action 

When iron or nickel carbonyl comes into contact 
with moist air, dissociation into carbon monoxide 
and a finely divided metallic salt takes place. This 
salt appears to be a hydrated basic carbonate of 
somewhat uncertain composition. Thus, when a per- 
son is exposed to an atmosphere into which iron or 
nickel carbonyl has been released, he breathes a 
mixture of varying proportions of the metallic car- 
bonyl, carbon monoxide, and a dust of finely divided 
metallic salt. What part each of these components 
may play in the toxicological picture will be discussed, 
but for the moment the discussion will be limited to 
the overall effects of inhalation of an atmosphere 
known to contain originally iron or nickel carbonyl. 
Since the physiological action of the two compounds 
is essentially the same, they will be discussed to- 
gether. 

Armit in 1907 described the sequence of events 
in human cases of nickel carbonyl poisoning as fol- 
lows: 

. . . immediately after having been exposed to air contain- 
ing plant-gas there was giddiness, and at times dyspnea and 
vomiting. These symptoms passed off rapidly as soon as the 
patients were brought into the fresh air. After 12 to 36 hours 
the dyspnea returned, cyanosis appeared, and the temperature 
began to be raised. Coughing with more or less blood-stained 
sputum occurred on the second day or later. The pulse rate 
became increased but not in proportion to the respiratory 
rate. Delirium of varying types frequently occurred, and a 
variety of other signs of disturbance of the central nervous 
system was noted. Death took place in the fatal cases between 
the 4th and 11th days. The chief changes found post mortem 
were hemorrhages in the lungs, edema of the lungs, hemor- 
rhages in the white matter of the brain (in one case this was 
very extensive), while some doubt exists ^ to whether any 
blood changes were present. 

This sequence of events parallels closely that of a 
fatal case of human nickel carbonyl poisoning de- 
scribed in 1934,^2 in which death occurred on the 
seventh day following exposure. The reaction of 
mice, rabbits, cats, dogs, guinea pigs, and goats is 
similar to that of 

If masked troops are exposed to air containing 
iron or nickel carbonyl, the carbonyl is catalytically 
decomposed in contact with the active carbon of the 
mask, leaving the finely divided metallic salt and 
carbon monoxide. The metallic dust is efficiently 
retained by the particulate filter of the service mask. 


SECRET 


NICKEL CARBONYL AND IRON CARBONYL 


177 


but the carbon monoxide passes through. When 
mice were exposed to atmospheres which had origi- 
nally contained iron or nickel carbonyl but which 
had then been passed through active carbon, deaths 
which occurred were entirely due to carbon monoxide 
and bore no similarity to those resulting from ex- 
posure to the carbonyls per The effect of the 

carbonyls on masked troops, therefore, is quite dif- 
ferent from their effect on unmasked troops. 

11.4.2 Toxicology 

The toxicity of iron and nickel carbonyl by inhala- 
tion is shown in Tables 4 and 5. These data leave 


Table 4. Toxicity of iron pentacarbonyl. 
All concentrations were nominal. 


Species 

Ct 

(mg min /I) 

Exposure 

time 

(min) 

Mortality 

Reference 

Mouse 

73 ±24 

10 

LiCtho 

13 


75 

10 

49/50 

7 


70 

10 

6/10 

7 


61 

10 

4/10 

7 

Rabbit 

90 

45.5 

lethal 

70 


Table 5. Toxicity of nickel carbonyl. 

A = analytical concentration; N = nominal concen- 
tration. 

Species 

Ct 

(mg min/1) 

Exposure 

time 

(min) 

Mortality 

Refer- 

ence 

Mouse 

1.7 A 

10 

L{Ct)^o 

7 

Rat 

5.1 A 

10 

1/5 

9a 

Guinea pig 

5.1 A 

10 

0/1 

9a 

Rabbit 

5.1 A 

10 

0/1 

9a 


73-76 N 

50.5 

64/77 

70 

Dog 

5.1 A 

10 

0/1 

9a 


217 N 

75.5 

lethal 

70 

Cat 

5.1 A 

10 

0/1 

9a 


241 N 

75.5 

25/30 

70 


much to be desired, but the picture is obscured partly 
because of the uncertainty as to the composition of 
the gas mixture breathed (the relative proportions of 
carbonyl, carbon monoxide, and metallic salt), and 
partly because some of the concentrations are nom- 
inal and hence may be grossly inaccurate. It would 
appear from the data shown, however, that iron 
carbonyl is less toxic to mice and rabbits than nickel 
carbonyl. 

Carbon monoxide produced in air or in vivo by the 
dissociation of the carbonyls would, of course, com- 
bine with hemoglobin to form carbon monoxide 


hemoglobin, and this in turn if produced in sufficient 
quantity leads to death by asphyxiation. There is 
evidence, however, that carbon monoxide does not 
play a significant part in death resulting from ex- 
posure to a minimum lethal dose of the carbonyl, 
since: (1) animals killed with nickel carbonyl had at 
the time of death only 5 per cent carbon monoxide 
hemoglobin; (2) animals whose blood contained 32 
per cent carbon monoxide hemoglobin from pre- 
exposure to pure carbon monoxide actually lost car- 
bon monoxide during exposure to a fatal dose of 
nickel carbonyl; (3) iron carbonyl yields 1.25 times 
as much carbon monoxide per mole as nickel car- 
bonyl, but is less toxic than the latter; (4) the pa- 
thology resulting from exposure to minimum lethal 
doses of iron or nickel carbonyl does not resemble 
that produced by carbon monoxide.'^® Thus, carbon 
monoxide does not play an important role in poison- 
ing from minimum doses of the carbonyls, although, 
if larger quantities of the carbonyls are present, it 
may contribute to the pathological picture. 

If carbon monoxide effects are of no consequence 
in minimum lethal dosages of the carbonyls, the toxic 
effects must be due to inhalation of either the un- 
changed carbonyl or the finely divided metallic salt. 
It was observed that when nickel carbonyl was 
released into a gas chamber a smokiness rapidly ap- 
peared as a result of the formation of a cloud of small 
particles of nickel salt. Fundamental studies of the 
rate of breakdown of nickel carbonyl in the presence 
of air and moisture led to the hypothesis that nickel 
carbonyl would be completely dissociated either be- 
fore or soon after reaching the alveoli of the lungs. 
On this basis, the toxicity of nickel (or iron) car- 
bonyl was attributed entirely to the metal and to the 
fact that the metal is introduced into the lungs in 
such a fine state of subdivision that it readily pene- 
trates to the alveoli.'^® By tissue-staining techniques 
the presence of nickel was demonstrated in the mu- 
cous membranes of the respiratory tract and in the 
free surfaces and tissue immediately surrounding the 
surface of the bronchi, bronchioli, and alveoli. Stain- 
ing was intense at the free edges and diffuse in the 
neighboring tissues.^® 

If the toxicity of the carbonyls is entirely due to 
the metallic part, the parenteral administration of 
the metal in question or its salts should produce es- 
sentially the same effects as the inhalation of the 
carbonyls. This experiment was performed,^® and, 
when finely divided nickel salts were injected sub- 
cutaneously or intraperitoneally in guinea pigs, rab- 


SECRET 


178 


CADMIUM, SELENIUM, AND CARBONYLS OF IRON AND NICKEL 


bits, or cats, in doses which were calculated to be of 
the same order of magnitude as those found lethal 
for the carbonyl by inhalation, the course of the 
poisoning and post-mortem changes in lungs, brain, 
and adrenals were said to be similar to those found 
in nickel carbonyl poisoning. The intravenous injec- 
tion of nickel carbonyl in rabbits has also been found 
to produce lung edema and damage to the lung capil- 
laries.^® The injection of iron or its salts is said to 
have produced symptoms and pathological changes 
similar to those resulting from the inhalation of iron 
carbonyl.'^® 

In rabbits the lethal dose of nickel by subcutane- 
ous injection was approximately 7.5 mg/kg, by in- 
traperitoneal injection about 7 mg/kg, and by in- 
halation ^ of the carbonyl about 3 to 4 mg/kg. '^® 
With cats the lethal dose of nickel was about 12.5 
mg/kg by subcutaneous injection as compared with 
about 8.5 mg/kg by inhalation of nickel carbonyl.* 
The lethal dose of iron when given by intraperitoneal 
injection to rabbits was about 20 mg/kg. The slightly 
greater apparent toxicity of the carbonyls over the 
metallic salts was attributed to the fact that the 
lungs offer a more favorable surface for rapid ab- 
sorption than the sites of subcutaneous or intraperi- 
toneal injection.^® However, the calculated inhalation 
dosages in these experiments were based on nominal 
concentrations of the carbonyl, and it is possible that 
the true inhalation dosages were very much lower 
and that the agreement between the lethal dose of 
carbonyl by inhalation and of the metallic salts by 

^ Inhalation concentrations were nominal, and hence inha- 
lation dosages may have been greatly overestimated. 


injection is fortuitous. The question of whether the 
carbonyls are more toxic than the metallic residue 
liberated by their decomposition can only be an- 
swered by studying the effect of breathing such 
metallic dusts uncomplicated by the presence of 
either carbon monoxide or the unchanged carbonyl. 
Nevertheless, a qualitative (and perhaps quanti- 
tative) correspondence is reported between the effects 
produced by the inhalation of the carbonyls and 
those produced by injection of the corresponding 
metallic salts. 

11.4.3 Assessment of Value as 

Chemical Warfare Agents 
The intrinsic toxicity of the carbonyls is probably 
too low to recommend them as primary chemical 
warfare agents except under very special conditions. 
If used as sources of carbon monoxide for mask- 
breaking operations, they might have limited appli- 
cation in the attack of enclosed fortifications, but 
more efficient mask-breakers are known (e.g., cyan- 
ogen chloride, see Chapter 2). It should be borne 
in mind, however, that the carbonyls are inflamma- 
ble, miscible with petroleum products, and thus 
suitable adjuvants to flame thrower fuels. In flame 
thrower operations there are frequently situations 
such as in the attack of enclosed fortifications where 
considerable advantage could be gained from the 
high carbon monoxide concentration and toxic dust 
resulting from the incomplete combustion of fuels 
fortified with the carbonyls, and this aspect of their 
use undoubtedly merits careful consideration and 
further investigation. 


SECRET 


Chapter 12 

RICIN 


12.1 INTRODUCTION ^ 

T he isolation of the toxic protein ricin from 
castor beans and the investigation of its proper- 
ties from the standpoint of assessment as a possible 
chemical warfare agent were studied under Divi- 
sion 9 of the National Defense Research Committee 
[NDRC] during the period 1942-1945. Earlier work 
by British investigators had shown that ricin (com- 
monly coded as “W”) could be dispersed as a par- 
ticulate, nonpersistent, toxic cloud by explosion of 
bombs containing a suspension of ricin in carbon 
tetrachloride. Notable progress was made by NDRC 
investigators in all phases of the work with ricin. 

Processes for the extraction of ricin from castor 
beans and cold-pressed castor bean pomace were the 
subject of laboratory and pilot plant studies. During 
the laboratory investigations the protein was crystal- 
lized; the crystals were not completely homogeneous 
but represent the purest ricin so far obtained. The 
pilot plant development culminated in a process of 
extraction of castor bean pomace with water and 
purification of the toxin by two precipitations with 
sodium sulfate. A water solution of the purified toxin 
was spray-dried to give a dry product with a mass 
median diameter of 6-8 This was air-ground to 
give “dispersible ricin” with a mass median diameter 
of 2. 5-3. 5 Ai, which was approximately half as toxic 
(by injection) as crystalline ricin. 

Early work on the physiological action of ricin 
resulted in the development of a bioassay procedure 
in mice which was used to determine the toxicity 
of various ricin preparations. Later studies investi- 
gated the inhalation toxicities of various ricin prepa- 
rations, which are a function of the intrinsic toxicity 
of the material and the particle size distribution in 
the inhaled particulate cloud. 

Toxoids have been prepared from ricin by various 
means, most successfully by treatment with formalin. 
The toxoid has been used to produce in horses and 
rabbits antiricin serums. These have been purified 
and concentrated as antiricin globulin fractions that 
were made available for therapy in case of accidental 
exposure. Immunization against ricin appears im- 
practical at present because of the short duration of 

» By Arthur C. Cope. 


passive immunity in animals, and the toxicity and 
local necrotizing action of toxoid preparations avail- 
able for use in inducing active immunity. 

The detection and assay of ricin in the field is a 
difficult problem. Sensitized guinea pigs afford the 
most sensitive, rapid, and specific means of detection 
through their anaphylactic response. Hemagglutina- 
tion and precipitin tests have been used; chemical 
tests are less specific. Determination of particle size 
distribution forms an important part of the assess- 
ment of ricin and all other particulate clouds (see 
Chapter 15). Field trials employing these analytical 
means and animals exposed to the clouds to deter- 
mine toxicity have been conducted to evaluate ricin 
as a war gas and determine the efficiency of various 
munitions for its dispersal. 

Ricin is most efficiently dispersed from small high 
explosive-chemical bombs as a suspension in carbon 
tetrachloride of the most finely divided material 
available. On the basis of airplane stowage such 
bombs are estimated to be seven times as effective 
as bombs charged with phosgene. 

Processing all of the castor beans used in this coun- 
try (based on 1941-1944 consumption) by the opti- 
mum procedure based on pilot plant experience 
would yield approximately 1,000 tons of dispersible 
ricin annually at a cost of about $13 per pound. This 
is a significant quantity of a material which might 
be used as a unique nonpersistent agent in gas war- 
fare, difficult to detect and disturbing to morale be- 
cause of its delayed toxic action. Ricin has served as 
a model substance, presenting problems in prepara- 
tion, protection of personnel, detection, assay, and 
dispersal similar to those presented by other materi- 
als investigated in the field of bacteriological warfare. 

Some minor duplications appear in the subsections 
of this chapter, which were written by different 
authors. 

12.2 PREPARATION OF RICIN ^ 

The isolation from castor beans of products con- 
taining the toxic principle known as ricin has been 
recorded many times in the open literature within 
the past 60 years. During World War I ricin was 

^ By Joseph Dec. 


SECRET 


179 


180 


RICIN 


examined as a candidate chemical warfare agent and 
its preparation was studied. The investigation of 
the preparation and properties of ricin pertinent to 
its use as a chemical warfare agent was renewed in 
Great Britain early during World War II and in 
this country under NDRC Division 9 during the 
fall of 1942.1-4 

The objective of developing a process for the large- 
scale production of ricin in a form suitable for dis- 
persion from munitions was attained. ^ During the 
course of this development about 3,800 lb of ma- 
terial was produced on a pilot plant scale.i-ii-^^ Also 
of considerable importance was the preparation of 
ricin in a crystalline form ^ for the first time. 

A complete review of the great number of products 
containing ricin whose preparation has been recorded 
both in the open and classified literature is beyond 
the scope of this chapter. Emphasis is placed herein 
on the products studied most extensively during 
World War II and on the studies leading to their 
preparation. These include crystalline ricin; two 
products used in field trials with munitions, 470 BM 
199 and L703; and the material used for the prepa- 
ration of toxoid, Bl. A process for the large-scale 
production of ricin is outlined. 

12.2.1 Crystalline Ricin 

The isolation during the late summer of 1943 of 
the material responsible for the toxicity of crude 
ricin preparations in crystalline form was a signal 
achievement. 2 Neither the first crystals isolated nor 
any of the crystalline materials subsequently pre- 
pared 42.15 could be shown to be single substances.^ -4® 
Since the crystalline material was the most toxic 
fraction ever isolated from crude ricin, studies were 
initiated to determine its physical and chemical 
properties, composition, and physiological behavior. 

Properties 

The crystalline material is a protein of the globulin 
type,2'45 although the crude toxin shows albumin-like 
solubility behavior. Repeated crystallizations fail to 
increase its toxicity,^ ’4^ which has been assayed to 
be 500 ® and 750 42 TU (depending on the method of 
evaluating TU; for definition of the toxicity unit 
known as TU see Section 12.5). The protein is soluble 
in acid or alkaline solution, is least soluble in the 
range of pH 5.0 to 8 . 0 ,^ -42,15 jg more soluble in the 
presence of other proteins.2-4® Its ultraviolet light 
absorption spectrum is similar to that of a typical 
protein,2-45 and it has a specific optical rotation of 


— 26.^ Ultracentrifuge and electrophoresis measure- 
ments showed the material to be fairly homogene- 
ous.^-^ However, solubility measurements indicated 
the crystalline material to consist of a solid solution 
of more than one component.2-4^ On the basis of 
sedimentation and diffusion studies the molecular 
weight has been estimated at 36,000 ^ and 77,000.^ 
The rate of denaturation of the crystalline material 
in aqueous solution to a product insoluble at pH 5. 1 
has been determined at 65.3, 71.5, 78.1, and 86.5 C, 
and from pH 2 to pH 11.4^ 

The chemical composition of the crystalline ma- 
terial has been investigated, but not exhaustively. 
Evidence was obtained that the d-amino acid content 
of an acid hydrolyzate of the toxin cannot be more 
than 3 per cent. 4® On a moisture- and ash-free basis 
a sample of three times crystallized ricin was found 
to contain 16.23 ± 0.4 per cent nitrogen. 4® From the 
titration curve of crystalline ricin in water and in 
the presence of 8 per cent neutral formaldehyde the 
numbers of basic, amino, imidazole, and carboxyl 
groups were deduced. 4® The amide nitrogen, alkali 
labile ammonia, hydroxyamino acid, arginine, his- 
tidine, aspartic acid, and glutamic acid 4® contents 
have been determined by chemical analysis. The 
amino acid analyses referred to account for 50 per 
cent of the weight of the protein and 60 per cent of 
the nitrogen. The protein was found to contain 1.34 
per cent sulfur and less than 0.1 per cent phos- 
phorus. 

Preliminary to the first successful crystallization, 
ricin-sodium sulfate cake, an amorphous product 
(described in Section 12.2.5), was fractionated with 
ammonium sulfate at pH 6.8 to concentrate the 
toxin. 2 The moist solid was dissolved in a minimum 
of water and allowed to stand at 5 C. A granular pre- 
cipitate formed, which gradually became crystalline 
on standing for several weeks. The crystals were 
isolated, suspended in water, and dissolved by the 
addition of a little hydrochloric acid. The solution 
was adjusted to pH 6.8 and allowed to stand at 5 C. 
Recrystallization was complete in 2 or 3 days. 

Crystallization procedures more rapid and pro- 
ductive than the original method were developed. 42 -i® 
Two extractions of the ricin-sodium sulfate cake 
with 10 parts of sodium sulfate solution (19 g Na 2 - 
SO4/IOO ml H 2 O) were found to leach away many 
of the gummy low molecular weight impurities with- 
out appreciable loss of the toxin. 4® One useful pro- 
cedure 4® involved extracting the residue with water 
and allowing the solution to stand overnight in a 


SECRET 


PREPARATION OF RICIN 


181 


refrigerator. The precipitate which formed was re- 
moved and dissolved in water with the aid of a little 
acid. The solution was neutralized, seeded with a few 
crystals, and stored in the cold for several days to 
yield a crystalline precipitate, which was separated 
and recrystallized. A modification of this procedure 
was performed starting with 1 kg of ricin-sodium 
sulfate cake.^^ The yield was about 70 g of crystalline 
material, which is 7 per cent by weight or about 
35 per cent of the toxin content of the starting ma- 
terial. Recrystallization was complete in 12-36 hours 
with an 85-90 per cent recover}^ 

A 2- to 234-hour dialysis of a 20 per cent aqueous 
solution of ricin-sodium sulfate cake also served to 
remove the low molecular weight impurities. The 
dialyzed solution after filtration and standing in a 
refrigerator yielded a crystalline precipitate. The 
percentage yields were comparable with those ob- 
tained in the procedure involving preliminary puri- 
fication with sodium sulfate solution. 

In an attempt to obtain a pure sample of ricin for 
an absolute standard, 60 g of 4 times crystallized 
material was extracted 25 times wdth 0.1 per cent 
sodium sulfate solution at pH 7.0 and 10 The 
residue of about 6 g was recrystallized. Solubility 
studies on this product have not yet been made. 
Although the product is probably the purest sample 
of ricin obtained thus far, its allergen content has 
been estimated at about 0.1 per cent on the basis of 
animal assay. 

Numerous experiments were performed in the 
study of the crystallization of ricin which led to the 
procedures just described.^ Flotation-purified 
ricin and the ball-milled and hammer-milled products 
(described in Section 12.2.5) were less satisfactory 
than ricin-sodium sulfate cake as the starting ma- 
terial; however, crystalline material has been ob- 
tained from flotation-purified ricin. Although a 
short dialysis of a solution of ricin-sodium sulfate 
cake is satisfactory for the preliminary purification, 
exhaustive dialysis is not.^^ Some impurities can also 
be removed by adsorption on Celite or floridin.^^ 

12.2.2 Amorphous Ricin 

Studies on the preparation of amorphous ricin have 
been extensive and a great number of products of 
varying properties and content of toxin, non toxic 
protein, proteose, and salt have been obtained.'*-®’^^’^ 
Crude ricin is soluble in water and dilute salt solu- 
tions. In the dry state the products are normally 
stable at room temperature and denatured at ele- 


vated temperatures.'^’^®*’^^ The stability decreases 
with increasing moisture content.'**^®'^ Aqueous solu- 
tions are less stable than the dry product at both 
room and higher temperatures.'^ 

Starting Material for Preparation of Ricin 

Samples of ricin prepared from castor beans of dif- 
ferent sizes and colors seem to be identical in physi- 
cal, chemical, and immunological properties. The 
maximum variation in toxin content of the different 
beans which were examined in one laboratory was 
34 per cent.'^ 

The beans contain about 50 per cent oil and the 
toxin is best isolated after removal of a substantial 
portion of this oil. The castor bean pomace which is 
obtained in the laboratory using a Carver press ^ or 
in industry using a hydraulic press contains about 
15 per cent oil and is satisfactory for the aqueous ex- 
traction of the toxin. A pomace containing 1-2 per 
cent oil can be prepared by extraction of either 
ground castor beans or cold-pressed pomace with 
suitable organic solvents.'^’^'^ If desired, the bean hulls 
can be removed from the pomace by flotation in or- 
ganic solvents.'^’^^ 

Hydraulic-pressed castor bean pomace is prepared 
commercially by castor oil producers. In one of the 
commercial processes the castor beans are ground, 
heated to about 60 C, and pressed. This cold- 
pressed pomace is recommended as the starting ma- 
terial for the large-scale production of ricin.^’^^ Com- 
mercially, this product is extracted four times with 
heptane at 82-87 C to obtain the remaining castor 
oil and then blown with steam to recover the residual 
heptane. The latter step also serves to detoxify the 
pomace, which is sold as fertilizer. Tests on a labora- 
tory and pilot plant scale showed that no appreciable 
detoxification occurs during the extraction with hot 
heptane.^ Efforts to find an economical procedure 
for recovery of the residual heptane without detoxi- 
fication of the pomace were unsuccessful.^^ Extrac- 
tion of the cold-pressed pomace with water at pH 3.8 
to remove the toxin and subsequent solvent extrac- 
tion yielded castor oil containing free fatty acid.^^ 

Extraction of Toxin from Bean Meal 

Among the solvents which have been used to ex- 
tract the toxin from castor beans or the pomace are 
water, dilute salt solutions, glycerol, ethylene glycol 
containing a little water, and diethylene glycol con- 
taining a little water. Water and dilute salt solutions 
are the most efficient and economical extractants for 


SECRET 


182 


RICIN 


the toxin.^ Ten per cent saline is slightly more effec- 
tive than water; however, it also dissolves more non- 
toxic material, most of which is coagulable protein.'^-^® 
About 33^-4 parts of water at pH 3.8 to 1 part of 
pomace seems to be most satisfactory. Less nontoxic 
protein is dissolved at pH 3.8 than at pH 7.0 and 
filtration is accomplished more easily.^ Extraction at 
temperatures approaching 70 C proceeds more 
rapidly than at room temperature but is accom- 
panied by denaturation of the toxin. ^ 

Isolation of Toxin from Aqueous Extract 
OF Pomace 

The toxin may be precipitated from the aqueous 
extract of pomace by nonaqueous solvents, by picric 
acid and similar precipitants, and by inorganic salts. 
Organic solvents such as alcohols and ketones pre- 
cipitate the toxin from aqueous solution but rapidly 
denature it at room temperature. At temperatures 
below 0 C acetone has been used to precipitate and 
wash the toxin. The use of ammonium sulfate,^ 
sodium chloride,"*'^^’^^ and sodium sulfate 3 . 4 , 11,15 fQj. 
precipitating and fractionating the toxin has re- 
ceived considerable study. Ammonium sulfate has 
been used for precipitating the toxin on a pilot plant 
scale. Sodium sulfate is now regarded as the best 
precipitant. It is superior to sodium chloride because 
it gives better fractionation, is less sensitive to 
changes in pH, and precipitates the toxin more com- 
pletely.^ The importance of temperature control 
during precipitation, filtration, and drying when 
sodium sulfate is used have been studied.^ Many data 
on the salting out of the toxin with different amounts 
of sodium sulfate and at different pH have been ob- 
tained. These data were useful in the develop- 
ment of the process for the large-scale production of 
amorphous ricin (Section 12.2.3).^^ 

Better yields of the toxin have been obtained in 
the laboratory than in the pilot plant.^’^^-^^ In the 
methods preferred by some investigators slightly 
less sodium sulfate is used than in the proposed large- 
scale process and the first precipitation is performed 
at pH 3.8. In one laboratory run,^® during which the 
isolation of the toxin was followed by chemical anal- 
yses and toxicity determinations, the product 
amounted to 2.3 per cent of the pomace weight. It 
contained 10.4 per cent nitrogen and 32.5 per cent 
inorganic material and had a TU value of 196. Of 
the toxicity present in the extract, 92 per cent was 
recovered. The product obtained at a similar stage 
in the pilot plant process amounted to 1.4 per cent 


of the pomace weight. Procedures involving a single 
precipitation of the toxin with sodium sulfate yielded 
in the laboratory products with TU values above 
200,^’^^ but these methods were not satisfactory on a 
pilot plant scale because of operational difficulties.'^’^^ 

Removal of water by lyophilization of solutions of 
partially purified ricin yields products of good ap- 
pearance and stability.^ Dialysis can serve to re- 
move much organic and inorganic impurity and in 
neutral solution leads to a precipitate of amorphous 
ricin. 

Comminution of Amorphous Ricin 

Since the toxicity by inhalation of ricin aerosols 
increases with decreasing particle size,® considerable 
effort was directed toward developing a method to 
produce finely divided, readily dispersible material 
without concomitant denaturation of the toxin. The 
process involving spray drying and air grinding of 
partially purified ricin was the best solution found to 
the problem. Prior to this solution an appreciable 
number of other methods were considered and ex- 
plored. 

The particle mass median diameter of freshly pre- 
cipitated crude ricin is 1-2 ^u, but as the moist filter 
cake is dried the particles agglomerate. The final 
precipitation was performed under various condi- 
tions with the objective of obtaining a product that 
could be ground readily to fine particles. Among the 
conditions investigated were temperature of precipi- 
tation, agitation during precipitation, addition of 
sodium sulfate as a dry powder or from saturated 
solution, variation in amounts of sodium sulfate used, 
addition of colloids, addition of seeding agents, addi- 
tion of nonionic wetting agents, and transfer of the 
freshly precipitated product to a volatile liquid. A 
2-hour ball-milling test was used for comparing all of 
the samples obtained in this series of tests. None of 
the experimental products showed significantly su- 
perior grinding properties. Lyophilization of solu- 
tions of partially purified ricin proceeds without de- 
toxification to give a friable mat-like solid. Ball- 
milling the solid reduced the particle size to a mass 
median diameter of 6 m in 33 per cent less time than 
that required with precipitated air-dried material. 
The detoxification which accompanied the ball- 
milling was 20 per cent less than with precipitated 
air-dried material. Lyophilization of a pomace ex- 
tract yielded a gummy product. 

Flotation-purified ricin-sodium sulfate cake (de- 
scribed in Section 12.2.4) was used in ball-milling. 


SECRET 


PREPARATION OF RICIN 


183 


colloid-milling, and hammer-milling experiments^^ 
Hammer-milling gave products with particle mass 
median diameters no smaller than 20 fx. Colloid- 
milling was even less effective. For about a year ball- 
milling appeared to be the most promising method 
for obtaining a finely divided material, and this 
method was investigated intensively. The opti- 
mum conditions using an Abbe 4-jar mill fitted with 
m gallon “specimen” type porcelain jars, which 
were found to give a 4- to 6 -m product, involved 
(1) steel balls for the milling, (2) low milling temper- 
ature ( — 20C), (3) low moisture content ricin, and 
(4) milling a suspension of ricin in carbon tetrachlo- 
ride.^^ Factors affecting the ball-milling that were 
studied included the vehicle, grinding media, temper- 
ature, time, and moisture content of the amorphous 
ricin. The ball-milling time necessary to give a 
4- to 6-At product was proportional to the load of 
ricin in the jar, 1 lb of ricin requiring 8 hours. Ball- 
milling a high moisture content material at room 
temperature or in the dry state resulted in more de- 
naturation of the protein than otherwise. Even under 
the above optimum conditions at least 50 per cent 
detoxification accompanied ball-milling the material 
to a mass median diameter of 4-6 The toxicity 
loss was reduced somewhat by drawing off the fine 
particles as they were formed.^^ 

A combination of spray drying and air grinding 
was found to give a product with a mass median di- 
ameter of 2. 5-3. 5 /JL with little denaturation of the 
starting material. A spray dryer was constructed 
and conditions for its operation investigated.^^ Fac- 
tors such as type of nozzle, solution concentration, 
atomizing air pressure, drying rate, drying temper- 
ature, and amount of drying air were studied. Under 
optimum conditions at an operating rate of 1 lb of 
product per hour the product has a particle mass 
median diameter of 6-8 /x and is 95 per cent soluble 
in water. The spray-drying process is superior to the 
ball-milling method from the standpoints of low 
toxicity loss, processing time required, safety, and 
cost. 

Several types of air-grinding equipment were in- 
vestigated for the comminution of spray-dried ricin. 

A grinder previously developed by the Eagle Pencil 
Company was found to be the best of the types ex- 
amined. Optimum conditions for its operation in a 
low humidity room were determined. Under optimum 
conditions the product with a particle mass median 
diameter of 2. 5-3. 5 m and a TU value of 225 is ob- 
tained at a rate of 1 lb per hour. A reduction in 


toxicity of about 5 per cent accompanies the air- 
grinding operation. 


12.2.3 A Process for the Production 
of Finely Divided Ricin 

On the basis of considerable laboratory and pilot 
plant data a process for the production of finely 
divided ricin at the rate of 26 lb per day has been 
outlined. The equipment and manpower necessary 
for this scale of operations have been determined. 
The process involves extraction of the toxin with 
water from castor bean pomace, two precipitations 
of the toxin by addition of sodium sulfate, spray 
drying of a solution of the partially purified toxin, 
and air grinding of the spray-dried material. It was 
estimated that the cost of such a pilot plant would be 
approximately $125,000 and that the cost of pro- 
duction at the 26 lb per day rate would be about 
$16 per pound. The cost of operating a plant to pro- 
duce 2,000 lb of “dispersible ricin” daily was esti- 
mated to be approximately $13 per pound of product. 
The product has a particle mass median diameter of 
2.5-3. 5 /X and a toxicity value of 225 TU. The yield 
is 0.65 per cent based on the pomace and would have 
amounted to about 1,050 tons annually during the 
years 1941-1944 if the castor beans crushed in this 
country during those years had been processed by 
this method. Reworking of the by-products from 
the spray-drying and air-grinding operations and 
reuse of the nitrogen-containing sodium sulfate sepa- 
rated in the flotation step should increase the yield 
to about 0.85 per cent. 

Starting Material 

The starting material for this process is commer- 
cially available hydraulic-pressed castor bean pom- 
ace which has not been solvent-extracted to remove 
the residual oil and subsequently steamed. The pom- 
ace produced by one company averages 8. 0-8. 5 per 
cent moisture, 14.0-16.0 per cent oil, and 4. 6-5.0 
per cent nitrogen. The pomace is ground in a ham- 
mer mill prior to extraction. 


Extraction of Pomace 

The recommended conditions for extraction of the 


toxin from pomace are as 
Water for extraction 

pH 

Acid to adjust pH 
Agitation time 


follows: 

350 per cent of pomace 
weight 
3.8 ± 0.1 
5 per cent H2SO4 
60 minutes (not critical) 


SECRET 


184 


RICIN 


Temperature of extraction 25 C 
Filtration Continuous vacuum fil- 

ter 

Filter aid 7 per cent of pomace 

weight 

Water for washing 50 per cent of pomace 

weight 

Under these conditions at least 97 per cent of the 
extractable toxin is recovered. The amount of water 
used is the minimum necessary to produce a slurry 
that can be handled satisfactorily in plant scale 
equipment. Sulfuric acid is preferred over hydro- 
chloric acid because of lower cost and lower corrosion 
rate. Continuous vacuum filtration at a higher pH 
is not possible because of the changed physical char- 
acter of the slurry. The filter aid is necessary to in- 
sure a satisfactory filtration rate. Filtration with the 
vacuum filter proceeds about 30 times faster than 
with a recessed plate type filter. 


First Precipitation and Filtration 


The optimum conditions for precipitation of the 
toxin from the extract and subsequent filtration were 
determined to be as follows: 


Salt usage 
pH 

Alkali to adjust pH 

Temperature 

Time of precipitation 

Filtration 

Filter aid 

Wash solution 


20 per cent Na2S04, based 
on filtrate weight 
7.0 

12 per cent Na2C03 
25 C 

20 minutes 

Continuous vacuum filter 
4 per cent of slurry weight 
20 per cent of 16.7 per 
cent Na2S04, based on 
weight of extract 


Under these conditions 50 per cent of the total 
nitrogen in the extract remains in solution and is 
eliminated in the filtrate, whereas less than 2 per cent 
of the toxin is lost. Precipitation at pH 7-8 was found 
to remove 6-10 per cent more non toxic nitrogen than 
at pH 3.8. Increasing the temperature from 25 to 35 
C and varying the precipitation time from 15 to 60 
minutes showed no appreciable effects. The rate of 
filtration with a vacuum filter was 33^ times that with 
a plate and frame filter press, filter aid being neces- 
sary to obtain a satisfactory filtration rate in both 
cases. 

A full-scale pilot plant run was made to determine 
whether a single precipitation process would give a 
product suitable for spray drying. Filter aid was 
not used, because previously it had been found not 


possible to reduce the sodium sulfate content of a 
product containing filter aid by a process involving 
flotation in carbon tetrachloride. Despite the absence 
of filter aid, which made the filtration very slow, the 
dried product separated very poorly in carbon tetra- 
chloride. The product, which amounted to 1.0 per 
cent of the original pomace, contained 11.0 per cent 
nitrogen and had a toxicity value of 200-250 TU. 
The operational difficulties encountered indicated 
this one-step process to be unsatisfactory on a pilot 
plant scale. 

Second Extraction and Filtration 
The optimum conditions for extraction of the toxin 
from the ricin-sodium sulfate-guhr moist filter cake 
were found to be as follows: 


Water for extraction 
pH 

Acid to adjust pH 

Filtration 

Water for washing 


300 per cent of wet cake 
weight 
3.8 ± 0.1 
5 per cent H2SO4 
Continuous vacuum filter 
25 per cent of slurry 
weight 


An additional 10 per cent (based on the pomace 
extract) of nontoxic nitrogen is removed during this 
operation. The pH was varied from 3.8 to 9.0, and it 
was found that 5 per cent (based on pH 3.8 extract) 
more nontoxic nitrogen is removed at pH 3.8 than 
at pH 9.0. The filtration is very rapid because of the 
large amount of filter aid present. 


Second Precipitation and Filtration 

The recommended conditions for the second pre- 
cipitation of the toxin and subsequent filtration are 
as follows : 


Salt usage 


pH 

Alkali to adjust pH 

Temperature 

Time of precipitation 

Filtration 

Filter aid 

Washing 


20 per cent Na2S04, allow- 
ance being made for the 
sodium sulfate in the 
filtrate 
7.0 

12 per cent Na2C03, or 
more dilute 
25 C 

45 minutes 

Plate and frame filter press 

None 

None 


Drying of the filter cake can be accomplished in 
6-10 hours using a three-section hot-air dryer oper- 
ated at successively increasing temperatures from 
55 C to 75 C. The dried product is given a slight 


SECRET 


PREPARATION OF RICIN 


185 


grind, passed through a five- to ten-mesh screen, and 
slurried in five parts of carbon tetrachloride. The 
toxin is removed from the surface of the mixture and 
dried. The sodium sulfate which settles to the bottom 
is used in the precipitation steps. 

A quantity of partially purified ricin was produced 
by the process outlined except that the product was 
dried at 50 C. The product was obtained in 0.85 per 
cent yield based on the pomace, contained 13.0 per 
cent nitrogen, and had a TU value of 250-300. 

Pilot plant tests indicated that a minimum of 20 lb 
of sodium sulfate is necessary to prevent loss of toxin. 
Approximately 3 per cent more nontoxic nitrogen is 
removed at pH 7.0 than at pH 3.8. Operation at 35 C 
instead of 25 C removes 2 per cent more nontoxic 
nitrogen, but about 2 per cent more toxin is lost. 
Since filter aid cannot be employed in this step, the 
use of a vacuum filter, which requires filter aid, is not 
possible. However, the physical character of this 
second precipitate permits a satisfactory filtration 
rate with a plate and frame filter press. Washing the 
filter cake with sodium sulfate solution (19.5 lb 
Na 2 S 04/100 lb H 2 O) does not result in sufficient puri- 
fication to warrant a washing operation. 

The utility of a third precipitation of the toxin 
with sodium sulfate was investigated. No appreciable 
purification was obtained without concomitant loss 
of toxin. 

Spray Drying and Air Grinding 

A 20 per cent aqueous solution of the above flota- 
tion-purified product is spray-dried under certain 
prescribed conditions at the rate of 1 lb per hour to 
give solid particles, which are 95 per cent soluble in 
water and have a mass median diameter of 6-8 /x- 
The solution for the second precipitation step can be 
spray-dried but it would contain about 50 per cent 
sodium sulfate. It was not found possible to separate 
the sodium sulfate from a spray-dried product by 
flotation in carbon tetrachloride. 

Air grinding of the spray-dried material is carried 
out under certain defined conditions in an air grinder, 
previously developed by the Eagle Pencil Company, 
at a rate giving about 1 lb of product per hour. This 
operation reduces the toxicity of the material about 
5 per cent. The product has a particle mass median 
diameter of 2.5-3. 5 m and a TU value of 225. 

12.2.4 Four Amorphous Ricin Products 

The four amorphous ricin products described in 
this section are of particular interest because of the 


considerable extent of studies performed with them. 
The preparations known as (1) ricin-sodium sulfate 
cake, (2) 470 BM 199, and (3) L703 represent suc- 
cessive stages in the development of an amorphous 
ricin product in a form suitable for dispersion from 
munitions, and (4) B1 was used for the preparation 
of a toxoid. 

Ricin-Sodium Sulfate Cake ^ 

A total of 1,550 lb of the product known as ricin- 
sodium sulfate cake was prepared on a pilot plant 
scale at the request of NDRC Division 9,^ and an 
additional 2,000 lb was prepared for the Canadian 
government. The method used in these operations, 
which was based on a procedure previously developed 
in another laboratory,'^ utilized the facts that crude 
ricin is soluble in water and insoluble in saturated 
aqueous solutions of sodium chloride and sodium 
sulfate. Subsequent studies resulted in a marked 
improvement in the method of preparation (Sec- 
tion 12.2.3).^^ 

Castor beans were the starting material and an 
Anderson expeller was used for expressing the oil 
from the beans. From each ton of beans was obtained 
810 lb of #3 grade castor oil. The expeller cake, which 
contained 13.1 per cent oil, 11.2 per cent moisture, 
and 4.6 per cent nitrogen, was ground in a hammer 
mill. Three parts of water at 15-20 C were mixed with 
the ground cake, the mixture agitated for 1 hour, the 
pH adjusted to 3.8 ±0.1 with 5 per cent hydrochloric 
acid, and the slurry filtered in a plate filter press. 

The filtered extract at pH 3.8 ±0.1 and 17 C was 
saturated with sodium chloride to precipitate the 
toxin. The precipitate was separated by filtration, 
sufficient guhr being used to insure a satisfactory 
filtration rate. A sample of dried filtered cake was 
found to contain 33 per cent guhr and 33 per cent 
sodium chloride. The wet precipitate was mixed with 
five parts of water and the mixture adjusted to pH 
8.0 with 5 per cent sodium hydroxide solution. The 
mixture was agitated for 1 hour and then filtered to 
remove guhr and other impurities. The filtrate was 
saturated with sodium sulfate, allowance being made 
for the sodium chloride present. The mixture was 
adjusted to pH 7.0 and then filtered at 35-40 C. The 
filter cake, about 1 inch thick, was dried in trays for 
60-72 hours at a maximum temperature of 60 C and 
then packaged. 

About 55 per cent of the toxicity available in the 
starting material was present in the ricin-sodium 
sulfate cake. The TU value of the cake was 100- 


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186 


RICIN 


125. Analysis of the product showed 4.4 per cent 
moisture, 46.6 per cent ash, and 8.6 per cent nitrogen, 
of w^hich 97 per cent was soluble and 45 per cent co- 
agulable.^ Electrophoretic and ultracentrifugal stud- 
ies indicated the cake to consist of several compo- 
nents with toxicity and hemagglutinating power 
associated with only the B1 fraction.^ Other studies 
indicated it to be composed of (1) the toxin, (2) a 
non toxic protein otherwise very similar in properties 
to the toxin, (3) a dye derived from the bean 
shells, (4) an allergen, (5) an unidentified substance 
which tends to keep the toxin in solution at pH 7.0, 
(6) proteoses, and (7) inorganic salts. 

Preparation 470 BM 199 

About 100 lb of the product designated as 470 BM 
199 w^as prepared “ for field trials at Dugway Prov- 
ing Ground and Suffield Experimental Station, 
Canada.'^^-^^ This ball-milled material was the best 
available in sizable quantities from the standpoint 
of high toxicity and small particle size for the field 
tests held during the spring and summer of 1944. 

Ricin-sodium sulfate cake was the starting ma- 
terial for the preparation of 470 BM 199. The cake 
was ball-milled for 15 minutes in an Abbe porcelain 
jar mill to yield a product that would pass through 
a 40-mesh screen and then slurried with 5 parts of its 
weight of carbon tetrachloride. The sodium sulfate 
tended to settle to the bottom of the mixture and the 
ricin concentrated at the surface where it was re- 
moved by scooping with a wire screen. This flotation 
step reduced the salt content of the cake from about 
45 per cent to 15-18 per cent. The flotation-purified 
ricin was suspended in carbon tetrachloride and the 
slurry ball-milled for 8 hours at room temperature 
in 134 gallon capacity Abbe porcelain jar mill using 
^-inch steel balls. The product was tray dried at 
60 C for 2 hours and then at 82 C for 13^ hours, 
which gave a white friable cake readily disintegrated 
by ball-milling for 5 minutes. 

Considerable denaturation of protein accompanied 
the ball-milling operation. The TU values found for 
different samples of this material ranged from 60 to 
100.^’^ Examination of a representative sample 
showed a particle mass median diameter of 6.3 /x, 4.4 
per cent moisture, 15.4 per cent ash, and 13.35 per 
cent nitrogen, of which 64 per cent was soluble and 14 
per cent was coagulable.® 

Product L703 “ 

A total of about 60 lb of spray-dried air-ground 
ricin was prepared. “ Lot L703 was examined in the 


laboratory for toxicity by inhalation after dispersion 
as a dust ® and similar lots L704 and L826 were tested 
in the field at the Suffield Experimental Station, 
Canada. The small mass median diameters, 3.1 m 
for L703 and 3.3 m for L826,2^^ are particularly note- 
worthy. 

The starting material for the preparation of spray- 
dried air-ground ricin was (1) ricin-sodium sulfate 
cake partially purified by flotation in carbon tetra- 
chloride, and included some (2) ball-milled and 
(3) hammer-milled products. Preliminary to spray 
drying, these materials were partially purified by 
another precipitation with sodium sulfate. The start- 
ing material was stirred with 4 parts of water, the 
pH of the mixture adjusted to 7.0 ± 0.1, guhr added, 
and the mixture filtered at 30 C. Sodium sulfate 
(16.2 per cent of filtrate weight) was added to the 
filtrate. The resulting slurry was adjusted to a pH 
of 7.0 + 0.1 and filtered at 30-35 C. The filter cake 
was dried at 60 C for 16 hours, ball-milled for 5 min- 
utes to pass a 40-mesh screen, and the sodium sulfate 
content was reduced by flotation in carbon tetra- 
chloride. Spray-drying 20 per cent aqueous solutions 
of this flotation-purified ricin gave materials with 
particle mass median diameters of 6-8 

The spray-dried materials were processed in an air 
grinder to yield products with TU values averaging 
200 and mass median diameters of 2. 5-3. 5 Analy- 
sis of lot L703 showed 2.0 per cent moisture, 19.7 per 
cent ash, 13.2 per cent nitrogen, of which 94 per cent 
was soluble and 45 per cent coagulable, a TU value 
of 160, and a mass median diameter of 3.1 

Preparation BU 

Preparation B1 is of interest because of its use for 
the preparation of toxoid. It was prepared as follows: 
73^ g of ricin-sodium sulfate cake, which contained 
71 mg of insoluble nitrogen and 650 mg of soluble 
nitrogen, was suspended in water and centrifuged. 
The precipitate was washed twice with 30 ml of 
water, to which was added for the second washing 
about 0.1 g of sodium sulfate. To the solution and 
washings (300 ml) was added 175 ml of warm satu- 
rated sodium sulfate solution to precipitate the toxin, 
and the mixture was allowed to stand overnight. The 
precipitate was centrifuged and reprecipitated twice 
from a volume of 150 ml with 87.5 ml of warm (37 C) 
saturated sodium sulfate solution. Additional toxin 
can be recovered from the filtrates. 

B1 is about two- thirds as toxic as the crystalline 
material. The molecular weight of B1 was determined 


SECRET 


PHYSIOLOGICAL ACTION 


187 


to be 85,000 and the isoelectric point to be 5.2. Crys- 
talline ricin and B1 seemed to differ only in toxicity, 
since by immunochemical, ultracentrifiigal, and 
electrophoretic criteria they appeared to be identical. 

12.3 PHYSIOLOGICAL ACTION « 

Systematic work on the use of ricin as a chemical 
warfare agent was begun in the United States during 
the fall of 1942. Its immediate objective was the pro- 
duction on a pilot plant scale of a sufficient quantity 
of an active product to make possible field trials of 
methods of dispersal of this novel type of agent. 
Such toxicological work as was done at this time was 
directed toward assisting in the control of the plant 
process and toward the accumulation of basic data 
on the inhalation toxicities of the product in various 
species of animal. 

When it became evident that the bulk production 
of a satisfactory material was feasible, ^ the ques- 
tion arose of the form in which it should be prepared 
for dispersal in the field. On the basis of experience in 
England,^® it was decided that it should be re- 
duced to a finely divided dry powder which could be 
introduced into munitions either in the dry state or 
in suspension in an inert volatile liquid. This decision 
made urgent the need for an extensive investigation 
of the relation between the particle size distribution 
in a toxic dust cloud and the inhalation toxicity of 
the cloud. Thereafter the chief emphasis of all as- 
pects of the program was on this complex problem. 
It was recognized that the significance of the pro- 
gram did not rest solely upon the potentialities of 
ricin as an agent for chemical warfare. Ricin was con- 
sidered, rather, as a readily available prototype of 
other unstable nonvolatile toxic agents of biological 
origin which might be exploited as offensive agents 
by one or other of the warring nations. 

The following subsection contains a summary of 
the available information on the parenteral and in- 
halation toxicities of standard preparations of ricin. 
This is followed by a review of the symptoms and 
pathology of ricin poisoning and a brief discussion of 
the mechanism of its action. 

12.3.1 The Parenteral Toxicity of Ricin 

Details of methods of bioassay, of methods of field 
detection and assessment, and of the relation of parti- 
cle size to inhalation toxicity will be found in Sec- 

^ By R. Keith Cannan. 


tions 12.5 and 12.6 and in Chapter 15, respectively. 
The summary which follows is concerned only with 
the toxicities for various species of standard prepa- 
rations of ricin under laboratory conditions. 

Ricin has been stated to be toxic for all verte- 
brates.® Frogs are sensitive only if kept in a warm 
environment.®® Few invertebrates appear to have 
been tested. The motility of a ciliate has been found 
to be arrested by low concentrations of ricin,® but the 
relation between this effect of a preparation and its 
toxicity for higher animals has not been established. 

The results of the few laboratories that have made 
comparative assays of a single preparation on a range 
of animal species are summarized in Tables 1 and 2. 
In Table 1 they are given as toxicities relative to the 
toxicity for the rabbit. The high sensitivity of the 
rabbit is well attested, but there is not full agreement 
on the order of sensitivities of other species. The ma- 
jority of the toxicities recorded in the literature have 
been based upon very few animals and are scarcely 
more than orders of magnitude. The most extensive 
series of observations are those made at the Uni- 
versity of Chicago Toxicity Laboratory [UCTL],^ 
but even these can be accepted as precise only for the 
mouse and for the rabbit. 


Table 1. Relative LDso’s (approximate) of ricin for dif- 
ferent species.* 


Author 

Osborne 

Field 

Hunt 

OSRD 55259 

Date 

1905 

1910 

1918 

1945 

Reference 

64 

56 

24 

9 

Route 

Subcu- 

Intra- 

Subcu- 

Subcu- 


taneous 

muscular 

taneous 

taneous 

Rabbit 

1 

1 

1 

1 

Rat 



1 

1.5 

Guinea pig 

7 

*8 

5 

3 

Mouse 



8 

8 

Sheep 




2 

Dog 


7 

16 

2 

Cat 


2 

16 

10 

Goat 


30 




* An entry of 10 in this table indicates that for the species in question, 
ricin was found to be one-tenth as toxic as for the rabbit, etc. 


In Table 2 some of the data on which Table 1 was 
based are given in absolute units. The preparation 
to which they refer exhibited about 28 per cent of 
the toxicity of crystalline ricin based on comparative 
assays on mice. Although the crystalline material is 
not believed to be molecularly homogeneous, it is 
definitely the most toxic material which has been 
prepared in contemporary work. It is suggested, 
therefore, that the best estimate of the attainable 
toxicity of ricin is obtained by dividing the LDso for 


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188 


RICIN 


Table 2. Estimated LD 50 (Mg/kg)- 


Author 

Osborne 

Field 

OSRD 55259 (10-day 
observation) 

Crystalline 
Standard ricin 

ricin* (computed) 

Rabbit 

0.5 (7-day) 
100 (2-day) 

0.1 

10 

3 

Rat 



15 

4 

Guinea pig 

3.2 (7-day) 
100 (2-day) 

0.8 

30 

9 

Mouse 



80 

24 

Sheep 



20 

7 

Dog 

500 (2-day) 

0.6 

20 

7 

Cat 

100 (2-day) 

0.2 

100 

30 

Goat 


3 (3-day) 




* The OSRD observations were made on the pilot plant product (stand- 
ard ricin). This had 28 per cent of the toxicity for mice of crystalline 
ricin. 


standard ricin by 3.5. The figures given in the last 
column of Table 2 have been derived in this manner. 

The very high toxicities recorded by Field for 
his preparation find no explanation. It is highly im- 
probable that they represent a product many times 
more toxic than crystalline ricin. On the other hand, 
his figures and those of Osborne do suggest that 
some of the early investigators of ricin succeeded in 
purifying the toxin to a degree approaching the 
purity of the crystalline material. 

The Relation of the Survival Time to the Dose 

The early investigators recognized that the time 
of survival of animals injected with ricin varied from 
a few hours to several weeks depending on the dose 
administered. This relation has been investigated 
for mice and, less extensively, for rats in several 
laboratories 5 . 9 . 15 , 42,61 j^gg formed the basis of the 
accepted method of bioassay (Section 12.5). The 
dose-survival time curves for mice obtained in one 
laboratory have been found to approximate rec- 
tangular hyperbolas which may be represented by 
the equations 

D{t — 11) = 430 (intravenous) 

D{t — 13) = 1,150 (intraperitoneal) 

D{t — 16) = 2,500 (subcutaneous) 

where t is the survival time in hours and D is the dose 
in micrograms of crystalline ricin per kilo body weight. 

Route of Injection 

The above results indicate that the relative toxic- 
ities for the mouse by subcutaneous, intraperitoneal, 
and intravenous injection, respectively, are (for the 
smaller doses) approximately 1/2. 2/6. The subcu- 


taneous and intravenous toxicities for the rabbit® 
are in the ratio of 1/5. 

12.3.2 Toxicity by Inhalation 

The importance of the particle size distribution of 
the airborne toxin has been emphasized in the intro- 
duction. In one extensive investigation of this prob- 
lem,® two methods of varying the particle size were 
used. In one, animals were exposed to atomized aque- 
ous solutions of ricin containing varying amounts of 
glycerol. The mean particle size in the aerosol varied 
with the amount of nonvolatile solvent in the solu- 
tion. The other type of experiment was the exposure 
of animals to dust clouds generated from powdered 
standard ricin which had been reduced to varying 
degrees of fineness by milling or spray drying. The 
results are summarized in Table 3. 


Table 3 

A. Inhalation toxicities of atomized solutions of standard 
ricin. 


MMD (m) 

LiCtho 

1.4 

(mg/min/m®) 

4.6 

6.6 

Rabbit 

4 

8 

10 

Guinea pig 

7 

15 


Mouse 

9 

40 

45 

Dog 

24 

45 


Cat 

24 

50 


Rat 

50 

120 


Monkey 

100 




B. Inhalation toxicities of dry dusts of standard ricin. 


Atomized 


Preparation 
MMD ( m ) 

Ball-milled 

10 6.3 

Spray-dried 
5.9 3.1 

solution 

1.4 

Mice 

Relative toxicities 

3.5 2.8 0.5 

6.5 

100 

Rabbits 

5.7 

5.3 


30 

100 

% mass below 

3 n 

7.5 

10.0 

3.0 

45 

100? 

% mass below 

2 n 

3.0 

3.2 

0.6 

8 

100? 


It would appear that the toxicity increased as the 
mass median diameter [MMD] of the cloud dimin- 
ished. Indeed, there is some justification for the con- 
clusion, in the cases of mice and rabbits, that the 
toxicity was roughly proportional to the fraction of 
the airborne mass which was present in particle sizes 
smaller than 2-3 m in diameter. The reader is re- 
minded that the MMD is an inadequate description 
of the characteristics of a dust cloud in which the 
particles differ in shape and density as well as in size 
and is referred to Chapter 15 for a discussion of the 


SECRET 


PHYSIOLOGICAL ACTION 


189 


relation of these factors to the probability that an 
inhaled particle will penetrate the nasal barrier. 

Although the most toxic aerosol was that with the 
MMD of 1.4 it is improbable that this represents 
the maximum attainable inhalation toxicity. Some 
allowance for nasal retention and for incomplete re- 
tention in the lungs should probably be made. Even 
so, the inhaled doses of the 1.4-/x aerosol for mice and 
rabbits, which may be computed from the minute 
volumes of respiration and the L{Ct) 5 oS, are approxi- 
mately equal to the LDso’s by intravenous injection.® 
That is to say, ricin is at least as toxic by inhalation 
as by vein. That it is probably more toxic in the 
lungs is indicated by the fact that the approximate 
LDso, when solutions were injected directly into the 
trachea of rabbits, was 0.5 /xg/kilo. In cats, dogs, and 
rats it was about 5 /xg/kilo.® In contrast with these 
results were the very low toxicities resulting from the 
nasal instillation of ricin.® 

When solutions of ricin are instilled in the eyes of 
animals in sufficient amount, enough may be ab- 
sorbed to be lethal.^^ Only small amounts are neces- 
sary to produce serious local injury. The instillation 
of 1.5 /xg of crystalline ricin produced corneal damage 
in a rabbit’s eye which disappeared in 10-14 days.® 
A particle of 100 m in diameter (0.5 ^g) implanted in 
the eye resulted in a conjunctival reaction persisting 
for a week. Corresponding lesions in the eyes of rats 
and guinea pigs required five to ten times this dose. 
It must be remembered that only large particles will 
impinge in the eye from a cloud and that such parti- 
cles will tend to precipitate rapidly under wind con- 
ditions favorable for the persistence of a fine particu- 
late cloud. Clouds of fine dusts such as are highly 
toxic by inhalation would therefore be unlikely to 
contain a concentration of coarse particles which 
would present a serious hazard to the eyes. 

12. 3. .3 The Toxicity of Ricin for Man 

The ingestion of two castor beans has been fatal in 
man.^'^’®^’®* It has been estimated that this corre- 
sponds with a lethal dose of about 0.3 mg of purified 
ricin per kilo. It has been suggested that ricin is 
about 100 times as effective by vein as by mouth.®® 
On this basis the intravenous lethal dose for man 
would be as small as that for the rabbit. Such com- 
putations are highly precarious, but other evidence 
has been advanced to indicate that man is quite 
susceptible to ricin poisoning. 

Elsewhere in this section are described symptoms 
of mild poisoning in a number of individuals who had 


probably been exposed to low concentrations of air- 
borne ricin. It is significant however that no serious 
casualty has occurred in the pilot plant, in the ex- 
plosion pit at Dugway Proving Ground, or in labora- 
tories studying the dispersal of ricin. The atmos- 
pheres in all these places must have been contam- 
inated with ricin dust. 

It has also been suggested that the handling of 
solutions of ricin presents a skin hazard,'^ but the 
opinion of most investigators who have long worked 
with such solutions is that the hazard is small if ele- 
mentary cleansing precautions are taken. 

12.3.4 Symptoms of Intoxication 

Laboratory animals show no evidence of intoxica- 
tion for several hours after the injection of a dose 
which will kill them in 24 hours. Thereafter their fur 
becomes ruffled, they grow restless, and refuse food. 
As the time of death approaches, diarrhea is frequent, 
breathing becomes dyspneic, their bodies feel cold to 
the touch, and their eyes may become sealed with 
exudate. Finally, the animals become moribund and 
die in coma or, more frequently, after a series of 
violent convulsions. With smaller doses the sequence 
of events is similar, but their time course as well as 
the initial latent period are more protracted. 

Some 150 cases of poisoning in man have been re- 
viewed. 2^®'*’®* Most of these have been the result of 
the accidental eating of castor beans. In some cases 
weakness and prostration were the only symptoms. 
In more serious attacks, there was nausea and vomit- 
ing, epigastric pain, cramps in the limbs, a weak 
pulse, and a rapid respiration with a rise in body 
temperature. Fatal cases passed into collapse fol- 
lowed by convulsions. Symptoms might be delayed 
for 2 to 14 days, or, surprisingly, might be evinced 
within 1 hour after ingesting the beans. 

Among the personnel working with ricin in the 
United States throughout 1943-45, there were no 
serious cases of poisoning, although there were a 
number of minor illnesses attributable to exposure. 
These were probably the result of inhaling airborne 
toxic dust. Two types of reactions among laboratory 
workers have been distinguished.® One — the im- 
mediate reaction — resembles that of an individual 
sensitized to a foreign protein. The symptoms have 
varied from a protracted bout of sneezing to a severe 
asthmatic attack with violent coughing and retching. 
The symptoms disappeared within an hour. The 
second type of reaction probably corresponds to the 
toxic effect in animals. Symptoms were delayed for 


SECRET 


190 


RICIN 


4 to 8 hours. There was then a sharp febrile response, 
tightness of the chest, tracheitis, aching joints, 
nausea, dyspnea, and coughing. Some hours later 
the onset of profuse sweating was commonly the 
signal of the alleviation of most of the symptoms. 

Somewhat similar observations have been made 
by the British, who have obtained local and general 
reactions by the intradermal injection of very small 
doses of ricin preparations (see Section 12.4.3). 

12.3.5 Pathology 

Accompanying the outward signs of intoxication 
in animals has been noted an early fall in body tem- 
perature,^ which may be preceded by a rise.^^ In 
rabbits, it has been reported that the blood pressure 
falls from 100 to 65 mm of mercury at an early stage 
and remains at this level until death. There appear 
to be no notable changes in the blood picture.^^ It is 
generally agreed 9-10-47.52 about 20 hours after 
the injection of an LZ) 50 dose there is a leucocytosis, 
with a simultaneous increase in both lymphocytes 
and polymorphonuclear leucocytes.^® A transient fall 
in red cell count has been recorded,®-^® but others 
report no change in red cell count, in red cell volume, 
or in sedimentation rate.^^ Within 20 hours after an 
LDso dose the clotting time was found to increase to 
three times its normal value and remain at this level 
till death several days later. ^ An extreme terminal 
hypoglycemia ^ and acidemia have been observed 
in rabbits and in rats and a rise in blood phosphatase 
has been reported. 

Careful reports of the gross and microscopic pa- 
thology of animals dying after the parenteral admin- 
istration of ricin are found in the early literature.®^~^’ 
This information is reviewed and extended in Chem- 
ical Warfare Service Monograph 37, written in 1918. 
Between this time and 1940, students of ricin became 
preoccupied with the chemical and immunological 
characterization of the toxin and with the hemag- 
glutinating activities associated with it. Little was 
added to our knowledge of the physiological action 
of the toxin. During World War II, extensive patho- 
logical examinations of animals poisoned with ricin 
were made in England,^® in the United States, 
and in Canada.^’ Some of these were confined to 
post-mortem examination of animals killed by the 
injection or inhalation of the toxin, whereas 
others relate to animals sacrificed at chosen times 
after the parenteral administration of lethal or 
sublethal doses. ^®’^* Bearing these differences in pro- 
cedure in mind, it may be said that there is substan- 


tial agreement between the laboratories referred to 
and the early reports in the open literature.^®~®^-®^ It 
is possible, therefore, to summarize the situation in 
the following general conclusions. 

Parenteral Administration 

1. There is mild to moderate congestion and 
edema of the lungs. 

2. There is mild degeneration of the intestinal 
epithelium at supralethal doses only. 

3. There is necrosis of the liver at and below 
LD50 doses. 

4. There is hyperplasia of the spleen at sublethal 
doses and involution at higher dosage. 

5. There is fragmentation and involution of the 
thymus at all doses. 

6. There is congestion and delayed necrosis of the 
adrenal in rats but not in rabbits. 

The occurrence of pin-point hemorrhages through- 
out the body has been emphasized by some but 
minimized by others. Less consistent findings have 
been necrobiosis of reticuloendothelial cells and bone 
marrow, cloudy swelling of the kidneys, and fatty 
degeneration of heart muscle. No differences be- 
tween the effects of crystalline ricin and of amorphous 
preparations have been observed ^® nor have any 
striking differences in the responses of different 
species been observed.® 

Inhalation 

The pathology is almost entirely confined to the 
thorax.® -22 The lungs are dark and greatly increased 
in weight and are filled with edema fluid. The ab- 
dominal organs are normal except for some fatty de- 
generation and, occasionally, hyaline infiltration and 
necrosis of the liver. 

Ingestion 

The effects of ingesting the toxin have been in- 
vestigated in fatal cases of poisoning in man.^^-^^.es 
The chief post-mortem findings have been extreme 
congestion of the stomach and intestines. 

12.3.6 The Mechanism of Action of Ricin 

Such pathological work as was carried out in the 
United States in 1943-45 was incidental to the pro- 
gram outlined in the introduction. No systematic 
investigation of the mechanism of action of ricin 
was undertaken and our knowledge of this subject 
remains fragmentary. We are, indeed, as ignorant 
of the nature of the action of ricin as we are of the 
actions of those bacterial toxins which exhibit a simi- 


SECRET 


IMMUNOLOGY 


191 


lar delayed effect and ill-defined pathology. Apart 
from revealing local effects depending upon the route 
of administration, pathological reports betray no 
characteristic lesions which would indicate the in- 
trinsic nature of the toxic action. 

The death of animals in convulsions is probably 
the result of hypoglycemia. It has been found that 
the blood sugar of rabbits and rats remains normal 
until a few hours before death, when it falls precipi- 
tously to convulsive levels. The toxic action, how- 
ever, is not primarily a reversible disturbance in 
carbohydrate metabolism. The liver glycogen is 
found to be very low at death, but it has not been 
possible to induce glycogen storage in poisoned ani- 
mals by injecting glucose to maintain a normal blood 
sugar level. Nor has life been prolonged by this 
means. 

One of the earliest theories of the action of ricin 
was that it was an enzyme. This was thought to ex- 
plain^its great potency. It was also thought that its 
delayed action might plausibly be attributed to the 
time required for the enzyme to build up a lethal con- 
centration of the hypothetical product of its activity. 
In this connection it should be borne in mind that 
several enzyme activities — phosphatase, lipase, 
esterase — are exhibited by extracts of castor beans. 
Purification of the toxin is not, however, accom- 
panied by enhanced enzyme activity. Indeed, it has 
been stated that crystalline ricin is free from phos- 
phatase and lipase action. ^2, 13 Recently a Canadian 
laboratory has reported that ricin preparations hy- 
drolyze adenosine triphosphate (ATP).'‘^-®® They 
further observed that ricin inhibited the beat of the 
isolated frog’s heart and that the beat was restored 
by the addition of ATP. This would suggest that 
ricin may act by interfering in those basic metabolic 
reactions whereby the energy of metabolism is con- 
veyed to the functioning structures of tissues. Data 
are, however, rfot yet available to indicate whether 
the concentration of crystalline ricin which is re- 
quired for effective adenosine triphosphatase action 
is such as to make plausible the hypothesis that its 
lethal action is dependent on this property. More- 
over, in one investigation ^ the action on the frog’s 
heart was not confirmed. No increase in nucleotide 
in the blood of animals poisoned with ricin was ob- 
served. Ricin did not cause a hydrolysis of ATP in 
the blood of dosed rats.®^ 

It may be submitted that it is just as plausible to 
attribute a disturbance in metabolism to the blocking 
or distortion by the toxin of the action of an enzyme 


native to the cells of the animal as to consider it to 
be the result of the invasion of those cells by a foreign 
enzyme in the form of the toxin. 

An earl}^ theory of the action of ricin was based on 
the hemagglutinating properties of ricin prepara- 
tion.2^’28 If this action were manifested in vivo pro- 
found disturbances in circulation might be respon- 
sible for the toxic effect. Unfortunately the concen- 
trations of ricin required to agglutinate red cells in 
vitro are greater than those established in body fluids 
by lethal doses of ricin. Moreover, the agglutination 
of red cells is inhibited by serum and crystalline 
ricin is very much less potent as an agglutinin than 
are cruder preparations.^ Finally, the absence of 
thrombotic lesions would seem to deny the theory. 
Although the hypothesis has little to support it, it 
should be recorded that tissue cells as well as erythro- 
cytes have been shown to be agglutinated by crude 
ricin and, in the case of the tissue cells, the action is 
accentuated rather than inhibited by addition of 
serum.^'^ 

One investigator has drawn attention to the 
similarity between intoxication by ricin and circula- 
tory shock. He has found some evidence of dimin- 
ished blood volume in poisoned rats and of reduced 
peripheral circulation in the rabbit. The latter effect 
he was inclined to attribute to pooling of blood in the 
splanchnic area. He considered, but dismissed, the 
thought that this condition might be due to capillary 
blockage resulting from agglutination in vivo. An in- 
cidental observation bearing on this question was 
that the rate of absorption of iron from the gut and 
the amounts deposited in tissues were increased in 
poisoned animals. He draws attention to a similar 
observation on animals in peptone shock.®® 

In conclusion it is worthy of remark that no effect 
of ricin on unicellular organisms or isolated tissues 
has been clearly established. Much more work in this 
field is desirable as are more detailed studies of the 
time course of metabolic disturbances in poisoned 
animals and the level of differentiation of tissue or- 
ganization and function at which susceptibility to 
poisoning first becomes manifested. 

12.4 IMMUNOLOGY ^ 

In the United States active research on the im- 
munology of ricin was initiated in February 1943 by 
NDRC Division 9 (Section 9.4.2, Immunochemical 

^ By Birdsey Renshaw. 


SECRET 


f 


192 


RICIN 


Studies). Related work was subsequently taken 
up by other NDRC investigators, by the 
Chemical Warfare Service, and by the 
Committee for Medical Research.^® At the time the 
NDRC research began there were available, in addi- 
tion to the open literature on ricin, an account of 
studies carried out for the Chemical Warfare Service 
during World War I and reports on preliminary 
work conducted in the United Kingdom during 1940, 
1941, and 1942.33,36.40,41 More recently Canadian in- 
vestigators have made a significant contribution. ^3 
The principal objective was to provide and eval- 
uate immunological procedures for protection against 
and treatment of ricin poisoning. With respect to 
protection, the aim — not yet attained — was the 
production of a toxoid which could practically be 
used to immunize troops. With respect to treatment, 
the problem — now satisfactorily solved — was the 
production and evaluation of potent anti ricin serums 
and antibody globulin preparations. A secondary ob- 
jective was the study and evaluation of immunologi- 
cal methods for detection and estimation. By- 
products of the immunochemical work have been 
significant contributions to the purification and 
physicochemical characterization of ricin. 

For purposes of orientation it may be stated at the 
outset that immunological, ultracentrifugal, and 
electrophoretic studies on ricin preparations from 
castor beans of different source and color have failed 
to reveal the existence of more than one heat-labile, 
toxic antigenic protein. On the other hand, a non- 
crystalline fraction (Bl) from castor beans, which 
by these criteria is identical with crystalline ricin, is 
not so toxic as the latter.^’^®° Furthermore, solubility 
studies do not reveal the crystals to be homogeneous.^ 
It is also known that castor beans contain, in addi- 
tion to heat-labile toxic protein, one or more heat- 
stable antigenic substances of low molecular weight 
(allergen); small amounts of allergen appear to be 
present even in crystalline ricin. ^'‘■^3 

12.4.1 Preparation of Ricin Toxoids 
Incomplete success has attended efforts to produce 
from ricin a toxoid possessing high antigenic potency 
coupled with negligible toxicity and skin-necrotizing 
properties. The available toxoids are satisfactory for 
eliciting vigorous antiricin production in animals. 
The best has been recommended for the active immu- 
nization of volunteers on an experimental scale but is 
not considered suitable for practical use in the routine 
immunization of troops. 


The most satisfactory toxoid has been prepared by 
formalinization of the toxin as follows: ricin at a 

concentration of 0.5 mg ricin nitrogen per milliliter in 
0.15M sodium chloride plus 0.02M phosphate buffer 
at pH 7.4 is treated with 5 per cent formalin for 
5 days at 37 C. Originally, partially purified pilot 
plant ricin (Bl fraction was used. 

Recently crystalline ricin has been utilized with sim- 
ilar results and will undoubtedly be employed in 
all future work. For best results the toxoid is pre- 
cipitated with alum or protamine. The resulting 
toxoid is about one- thousandth as toxic for mice as 
native ricin.^’^*'"’* However, subcutaneous injection 
of as little as 0.1 of the toxoid nitrogen produces 
skin necrosis in some rabbits,^^^ and in the form of an 
aerosol the toxoid is only about 15 times less potent 
than native ricin as a lung injurant. 

Some observers believe that formalinization in a 
more alkaline medium yields a better toxoid. Un- 
doubtedly a greater diminution of toxicity is effected 
under these conditions, but the indications are 
that antigenicity is more than correspondingly re- 
duced. 3 Precise evaluations of toxoids prepared 
at pH values differing by only 0. 1-0.2 unit are not 
available. The concentration of formalin is not 
critical; even high concentrations do not effect com- 
plete detoxification, and 0.5 per cent suffices to pro- 
duce a toxoid suitable for many purposes.^ Some 
consideration has been given to the chemical re- 
actions that occur during toxoid formation. 

No success has attended numerous attempts to 
produce a toxoid more effective than that just de- 
scribed. Among the procedures to which ricin has 
been subjected are the following: oxidation with 
chlorine or permanganate ; ultraviolet irradiation 
at low intensities 3.i8e,f f^j. short times at high 
intensities ; 3 . 1 su acety lati on ; ^ tryptic diges- 

tion; peptic digestion; treatment with nin- 
hydrin;^'^ and heating. A toxoid prepared by shaking 
ricin with toluene showed some promise in pre- 
liminary tests but remains to be completely evalu- 
ated. Injections of formalinized toxoid treated 
with normal serum and of specific precipitates of 
formalinized toxoid with antiricin rabbit serum 
proved unsatisfactory for active immunization.^’^*'" 
A few additional procedures have been suggested 
but were not evaluated before the work terminated. 

A finding of significance is that a purified but non- 
crystalline fraction (Bl) prepared from pilot plant 
ricin is immunologically identical with crystalline 
ricin but possesses only 60 per cent of the toxicity of 


SECRET 


IMMUNOLOGY 


193 


the latter.^ This observation suggested (1) that 
some form of detoxified ricin either exists in castor 
beans or is produced in the process of extraction and 
purification, and (2) that crystallization effects at 
least a partial separation of the toxic from the de- 
toxified material. That detoxified material immuno- 
logically indistinguishable from ricin is indeed pres- 
ent in castor beans is suggested by the further finding 
that crude aqueous extracts from the beans also pos- 
sess considerably more immunologically active ma- 
terial per unit amount of toxic material than does 
crystalline Up to now it has been possi- 

ble to effect only a very incomplete separation of the 
toxic and nontoxic fractions. However, further 
study of the conditions and factors responsible for 
the origin of detoxified ricin in castor beans might 
lead to a solution of the toxoid problem. In such 
work the changes which may take place in develop- 
ing and germinating beans should be examined. 

There is evidence that castor bean allergen is 
not completely removed from the heat-labile ricin 
by crystallization or even by repeated recrystal- 
lizations.^'^ Injections of a toxoid containing even 
small amounts of allergen conceivably might render 
men hy 4 )ersensitive to the allergen contained in sub- 
sequently injected toxoid, and to sublethal dosages 
of airborne ricin containing allergen. Some workers 
are inclined to minimize the practical importance of 
this possibility; to others it has been a source of 
great concern. Animal experiments bearing on the 
point are reviewed in Section 12.4.4, and limited 
human data are presented in Section 12.4.3. 

12.4.2 Antiricin 

Potent antiricin rabbit, horse, and goat serums 
have been obtained by a series of injections, first 
subcutaneous and subsequently intravenous, of ricin 
toxoids.^ Immunization can be continued with 
alum-precipitated but otherwise untreated ricin. For 
therapeutic purposes the hyperimmune serums may 
be used as such, but the antibodies are preferably 
purified to lessen the likelihood of immediate reac- 
tions and serum sickness. 

Standardization of Antiserums 

During World War II antiricin has been estimated 
with reference to an American Standard Antiserum 
arbitrarily assigned a potency of 100 units/ml.^®*^!^ 
Each milliliter of this serum® contains antibody 

® Available at the Medical Research Laboratory, Edgewood 
Arsenal. 


equivalent to about 7,500 mouse LD^o doses of ricin; 
that is, by the toxicity test described below it neu- 
tralizes 200 fjLg of crystalline ricin nitrogen or 
500 /xg of nitrogen of the relatively impure pilot plant 
preparation against which it was first tested. 

Two tests have been developed for the quantitative 
assay of antiricin titer: 

1. Toxicity-neutralization. Solutions of known 
amounts of ricin and of antiserum are mixed in 0.9 
per cent saline, incubated at 37 C for 34 hour, and in- 
jected intraperitoneally into mice. The minimum 
volume of serum in the mixture for which mice sur- 
vive for 10 days is considered to be equivalent to the 
amount of ricin used. The toxicity-neutralization 
test may be used to^letect as little as 0.2 unit of anti- 
body and is the method of choice if time permits. 

2. Inhibition of hemagglutination. Portions of 
ricin (e.g., 2 ng in saline) are mixed with decreasing 
volumes of serum and saline is added to a volume of 
0.8 ml. After incubation at 37 C for 34 hour, 0.2 ml 
of a 4 per cent suspension of washed human erythro- 
cytes of blood group 0 are added. The extent of 
agglutination is recorded after shaking and incubat- 
ing at 37 C for 1 hour. The minimum amount of 
serum which completely inhibits hemagglutination 
is considered equivalent to the amount of ricin used. 
Because of nonspecific inhibition by normal serum,^*'^ 
this test cannot be used to measure less than 5 units 
of antibody per milliliter.^*® In the choice of ricin 
for use in this test consideration must be given to the 
fact that the hemagglutinating properties can be re- 
versibly masked under some circumstances.* 

Potency of Antiserums 

The use of graded series of injections of ricin toxoid 
and/or native ricin has yielded in rabbits antiserums 
having potencies as high as 250 units/ml.* In horses 
serums possessing 150 units of antibody per milliliter 
have been obtained.* However, few animals have 
been observed with circulating antibody titers greater 
than that of the standard, and most animals in any 
series will attain titers more or less below it. Never- 
theless, the pooled serum from a group of adequately 
immunized rabbits possesses what can be considered 
for therapeutic purposes a high and effective titer. 

Purification of Antiricin 

To reduce the possibility of reactions from the 
therapeutic use of antiricin serum, methods which 
had been used for the partial purification of other 
antibodies were applied.* Sufficient experience has 


SECRET 


194 


RICIN 


been gained to make possible the production of con- 
centrated, partially purified horse or rabbit antiricin 
rapidly and on as large a scale as any program might 
require. 

Antiricin globulin from immunized rabbits was 
obtained in almost quantitative yield by 45 per cent 
saturation of the diluted serums with sodium sulfate 
at 37 C. The precipitate was dissolved in water, 
merthiolate added as a preservative, and the solution 
sterilized by passage through a Chamberland G\- 
ter.i*®-^ The ampouled material possessed an anti- 
ricin potency of 50 to 125 units/ml and was pre- 
pared in sufficient quantity for distribution to the 
Chemical Warfare Service and NDRC laboratories 
engaged in work on ricin. Prompt intravenous in- 
jection of 25 ml was recommended in the event of 
accidental inhalation of ricin aerosols. 

Horse antiricin was partially purified by isolation 
of the pseudoglobulin fraction or by peptic 

digestion by the Parfentiev method. The latter 
method was used to process 16 1 of horse plasma 
assaying 50 units of antiricin per milliliter. The yield 
was 1,090 ml of purified, modified globulin solution 
assaying 500 units/ml.^ 

Therapy with Antiricin 

Antiserum or purified antibody globulin is of con- 
siderable therapeutic value if promptly adminis- 
tered. Its effectiveness rapidly decreases with in- 
crease in the time between poisoning and therapeusis, 
and no benefit is obtained after the delayed symp- 
toms of poisoning have appeared.^ 

Serotherapy is effective against injections of at 
least several lethal doses of ricin if sufficient antiricin 
is administered promptly.®’^*’^^ Typical data for mice 
are presented in Table 4.^®^ 

After exposure to airborne ricin the pathological 
effects occur mainly in the lungs and the animals 
are not completely protected against pulmonary in- 
jury even by immediate therapy with injected anti- 
serum. However, the use of antiserum has defi- 
nite life-saving value up to 6 hours after gassing and 
is perhaps of limited benefit even as late as 10 
hours.®’^®^’'"’®^'^ Illustrative data are presented in 
Table The data reveal the desirability of utiliz- 
ing a large amount of antiricin. Equivalent amounts 
of rabbit antiserum, purified rabbit antibody globu- 
lin, and purified horse antibody pseudoglobulin ap- 

^ This material, put up in ampoules each containing 12 ml, 
is available at the Medical Research Laboratory, Edgewood 
Arsenal. 


Table 4. Therapeutic use of antiricin in mice poisoned 
with ricin by intraperitoneal injection.^*! 

Mice were injected intraperitoneally with about 20 
lethal doses (2 Mg of B1 ricin nitrogen) and subsequently 
injected intraperitoneally with ten times the neutralizing 
equivalent of antiricin (rabbit antiserum). 


Treatment 

0-24 hr 

Mortality 

24-48 hr 2-10 days 

Total 

No serum 
Serum 0.5 hr 

36 

0 

0 

36/36 

after ricin 
Serum 2 hr 

0 

0 

0 

0/37 

after ricin 
Serum 5 hr 

1 

0 

5 

6/38 

after ricin 

9 

3 

9 

21/37 


Table 5. Therapeutic use of antiricin in mice poisoned 
with ricin by inhalation.^*” 

Mice were exposed for 10 minutes to an aqueous aerosol 
of ricin at a nominal concentration (about 8 Mg B1 ricin 
nitrogen per liter) which was equivalent to at least ten 
times the LC 50 . Either 10 or 100 units of antiricin in the 
form of purified rabbit antibody globulin were adminis- 
tered intraperitoneally at various times after the exposure. 


Antiricin 

Time of 





admin- 

treat- 


Mortality 


istered 

ment 

0-4 days 

4-8 days 

8-10 days 

Total 

100 units 

None 

20 

0 

0 

20/20 


1 hr 

0 

0 

1 . 

1/17 


4 hr 

2 

3 

0 

5/19 


10 hr 

5 

9 

2 

16/18 


24 hr 

17 

3 

0 

20/20 

10 units 

None 

16 

0 

0 

16/16 


1 hr 

2 

4 

1 

7/20 


4 hr 

1 

10 

0 

11/18 


10 hr 

11 

7 

2 

20/20 


pear to possess approximately the same therapeutic 

efficacy. n 

Passive Immunity 

Passive immunity results from the injection of 
high-titer antiserum or partially purified antiri- 
cin.3,i8,3ia,b,c,e,f basis of these animal experi- 

ments, however, the protection cannot be expected 
to persist for more than 1 or 2 weeks at most. Thus 
passive immunization would have limited usefulness 
as a practical method for protecting troops. 

12.4.3 Active Immunization against Ricin 
Injection or inhalation of native ricin in small doses 
evokes antiricin formation and immunity 
in surviving animals. The response is sometimes 
striking, particularly after repeated administration 
of the toxin. Practically speaking, however, active 
immunization must be attained by the use of a 
toxoid. 


SECRET 


IMMUNOLOGY 


195 


Table 6. Resistance to airborne ricin of rabbits immunized with six injections of formalinized ricin.^^” 


The exposures in the gassing chamber were of 10 minutes’ duration. The 10-minute LC 50 for nonimmunized rabbits was 
about 0.5 Mg ricin nitrogen per liter. Thus the exposures were to approximately 4 and 20 times the L(Ct) 5 o dosage. 


Interval between 
last toxoid injec- 
tion and exposure 

Serum antibody 
titer before expo- 
sure (units) 

Cone, of ricin in 
gassing chamber 
(Mg nitrogen/1) 

Deaths in 10 
days 

Lung pathology 
in survivors 14 days 
after exposure 

Serum antibody 
titer in survivors 
14 days after 
exposure 

12 days 

0.8-3.3 

2.3 

0/10 

— to -1- + 4- 

1-8 


1. 0-3.3 

11.8 

3/9 

-h to -1- + + 

6.5-12 

3 months 

<0.2-0.8 

2.3 

0/7 

- to +-b-h 

8->30 


<0.2-0.2 

9.8 

4/7 

-|-+ to 4--f- + 

12->30 

5| months 

<0.2-0.6 

2.1 

3/8 

— to -b-h 

2-4 


<0.2-0.2 

11.0 

5/7 

+ to 4- + + 

8- >30 


Studies with Animals 

Several injection schedules have been used for 
studies with rabbits on the development of active 
immunity to inhaled ricin. The first schedule con- 
sisted of three subcutaneous injections at 5-day in- 
tervals of formalinized toxoid in the amounts of 
2.5, 5, and 10 /xg of ricin nitrogen per animal, respec- 
tively. This schedule resulted in circulating antibody 
levels of 1-3 units per milliliter and many animals 
survived exposure to about 20 L (Cl) 50 dosages of air- 
borne ricin 10 days after the last injection. However, 
the injections of toxoid produced severe skin re- 
actions with necrosis. A schedule of six injections 
conferred equal or greater immunity and the severity 
of the local reactions at the sites of injection was 
greatly reduced, although necrosis was not absent in 
all instances.^^^i’^®^’^^ A dosage sequence of 0.1, 0.2, 
0.5, 2, 10, and 20 jug of toxoid nitrogen is believed 
preferable to a schedule composed of doses of 0.1, 
0.5, 2, 5, 10, and 20 jug. 

Some of the characteristics of the antibody re- 
sponse and protection effected in rabbits by six 
toxoid injections are illustrated by the data of 
Table 6.^^® Maximum antibody response and pro- 
tection is attained 10 to 20 days after the last injec- 
tion. At this time the circulating antibody levels are 
1 to 3 units per milliliter of serum. The animals are 
immune to the lethal effects of at least several L(Cl ) 50 
dosages of airborne ricin, but the development of 
lung lesions is not prevented. Circulating antibody 
titer then falls progressively to reach levels of the 
order of 0.2 unit per ml after 2 to 4 months.^ 

In spite of the low level of circulating antiricin, some 
resistance to airborne ricin persists.^ 

After circulating antiricin has reached a low level, 
an injection of toxoid produces only a moderate in- 


crease in circulating antiricin. In contrast, a 
very striking increase in circulating antiricin, to 
5-30 units per ml of serum, is produced by a single 
exposure to a sublethal dosage of airborne ricin. 

The effect is to be seen when the exposure follows 
by only 12 days the last of a series of toxoid injec- 
tions. It appears to be more marked after longer 
times, when the circulating antiricin evoked by the 
toxoid injections has fallen to low values. A second 
exposure to airborne ricin does not elicit a pro- 
nounced further increase in the circulating anti- 
bodies.^*" These findings suggested that, for pur- 
poses of active immunization, controlled exposure to 
aerosols of ricin toxoid might effectively reinforce the 
effects of toxoid injections. No studies on immuniza- 
tion by inhalation of toxoid have as yet been made, 
however, except for one experiment in which previ- 
ously untreated rabbits were given a single exposure 
to airborne formalinized toxoid.^®® Twelve days later 
none of the survivors had developed a circulating 
antiricin titer as great as 0.2 unit per ml. Challenge 
exposures to airborne ricin were not made. 

Actively sensitized guinea pigs possess consider- 
able immunity against the toxic effects of ricin.* 
Subsequent to exposure to 15-40 L(C0 50 dosages of 
airborne ricin, a high proportion of the animals (i.e., 
31 of 33) that recovered from the initial anaphylactic 
reaction survived indefinitely. This degree of re- 
sistance was present in the three animals tested as 
late as 116 to 173 days after sensitization. 

Although the results show that considerable re- 
sistance to inhaled ricin can be achieved by immu- 
nization with formalinized toxoid, it has been empha- 
sized that the resistance has been measured by a 
statistical increase in the number of animals surviv- 
ing challenge exposures and that the surviving ex- 


SECRET 


196 


RICIN 


posed animals usualty develop lung lesionsd®^^ Some 
of these lesions are severe and apparently predispose 
the animals to bronchopneumonia. 

Human Immunization 

With regard to immunization of large numbers of 
troops, representatives of the Surgeon General 
(Army) have indicated that practical considerations 
make it highly desirable to limit the number of in- 
jections of toxoid to one or at most two or three 
spaced over a period of 4 to 6 weeks.^” The animal 
experiments give no reason to believe that effective 
immunization can be obtained with so few injections 
of currently available toxoids at doses sufficiently 
small to preclude very severe local reactions. There 
is, moreover, no evidence that effective immunity, 
if once produced, would persist at high levels for 
more than a few months. 

No experiments on human immunization have 
been made. However, the use of formalinized toxoid 
at a dosage schedule similar to that employed for 
immunizing rabbits has been recommended as safe 
for test with volunteers. It was felt that data on the 
local effects produced and on the levels of circulating 
antiricin attained would help to orient the further 
course of the work. 

Numerous serum samples from men working with 
ricin have been assayed for circulating antiricin by 
the toxicity-neutralization test.^-^*'^-®’”’'" No signifi- 
cant amounts of circulating antibody were found be- 
fore exposure to ricin. Considerable antiricin (i.e., up 
to 2.5 units/ml) was found in the serums of men who 
had handled ricin at the pilot plant for several 
months or more. The highest levels were found in 
men having histories of either cuts and abrasions or 
symptoms traceable to ricin. There is no direct evi- 
dence as to the degree of immunity possessed by 
these individuals. 

In the experience of the University of Chicago 
Toxicity Laboratory two types of reaction to acci- 
dental exposure to ricin have been observed. 
One, a delayed reaction, sets in after a latent period 
of 5 to 8 hours. A febrile response then occurs, ac- 
companied by tightness of the chest, tracheitis, ach- 
ing joints, nausea, dyspnea, and coughing. In 8 to 
12 hours the onset of profuse sweating has been ac- 
companied by alleviation of all symptoms except the 
cough and tracheitis, which sometimes persisted for 
several days. This reaction appears to correspond 
with the toxic reaction in animals. The second type 
of reaction is immediate and resembles that of sensi- 


tization. In mild cases violent sneezing of several 
minutes’ duration starts within a minute after ex- 
posure. In more severe exposures there have been 
asthmatic difficulties of breathing with violent cough- 
ing and retching; these symptoms disappear within 
an hour, leaving only a mild cough and a slight fever. 
Subjects who responded to exposure with an immedi- 
ate reaction did not show the delayed symptoms. All 
had worked with ricin over a prolonged period of 
time. Little or no antibody was found in serum sam- 
ples taken from four individuals following reactions 
of the immediate type.^’^^“ 

Somewhat similar observations were made earlier 
by the British and give some basis for interpreting 
the two classes of responses. It was found that 
some men working with ricin accidentally acquired 
immunity. Their serums contained antiricin, and the 
intradermal injection of ricin produced less than the 
usual amount of local damage. Other men became 
hypersensitive. Their serums contained no detecta- 
able antiricin. Intradermal injection of I Mg of toxoid 
produced immediate redness and swelling, in marked 
contrast to the usual effects of toxin which take many 
hours to develop. Moreover, the substance causing 
the immediate cutaneous response was not ricin, for 
it survived treatment with bleach or with heat suffi- 
cient to destroy the toxin. It would seem that the 
immediate responses which in men sometimes follow 
inhalation or injection of ricin preparations may be 
associated with hypersensitivity to castor bean al- 
lergen, whereas the delayed responses are, as indi- 
cated above, due to the toxic effects of ricin 
itself. 

A few British observations serve to emphasize the 
high sensitivity of men to the toxic effects of ricin. 
Intradermal injections of 0.3 Mg of a preparation 
which may have been about one-fifth as toxic for 
mice as crystalline ricin ^ produced a large area of 
inflamed swelling with some local necrosis. Similar 
injections of 1.3 Mg produced more marked local ef- 
fects and in addition pyrexia, leucocytosis, and 
malaise sufficient to keep the men off duty for several 
days. 

12.4.4 Immunological Methods for 
Detection and Analysis 

The principal immunological methods for detec- 
tion of ricin depend upon (1) the agglutination of red 
blood corpuscles by the toxin, (2) the precipitin re- 
action between ricin and antiricin, and (3) the ana- 
phylactic responses of sensitized animals. The rela- 


SECRET 


IMMUNOLOGY 


197 


live merits and limitations of these tests have been 
evaluated. 

Hemagglutination 

The agglutination of human red cells by ricin was 
used as a laboratory test for the toxin during World 
War It has also been studied and utilized in field 
tests during World War It is 

simple, rapid, and sensitive « to about 0.3 Mg of ricin 
nitrogen. In the form of a test developed during 
field trials it detected 10 Mg of ricin nitrogen in 1 min- 
ute, 4 Mg in 2 minutes, and 2 Mg in 5 minutes.^® Its 
specificity and sensitivity do not, however, match 
those of the other immunological methods, and as an 
analytical procedure it is at best only semiquanti- 
tative.^’^®"* It must be viewed with suspicion in the 
case of detection and analysis of unknown ricin 
samples because of the possibility that hemaggluti- 
nating properties can be masked.® 

Precipitin Reaction 

Although the addition of ricin to normal serum 
produces a precipitate under certain conditions, 
much smaller amounts suffice to produce a specific 
precipitate wdth antiricin serum. Thus the precipitin 
reaction is highly specific and sensitive; it is capable 
of detecting 1 Mg of I’icin nitrogen within 5 minutes, 
and much smaller amounts in longer times.®-^®^’^ 
Although less subject than hemagglutination to ex- 
traneous conditions, it must be borne in mind that, 
serum protein is precipitated by the ions of heavy 
metals which are present in smokes of various kinds.® 
With the limitation that different ricin preparations 
possess different ratios of toxic potency to immuno- 
logical activity (Section 12.4.1), the quantitative 
precipitin test affords a very accurate method for 
the estimation of ricin.® Under optimal condi- 
tions it is accurate to about 1 per cent. 

Anaphylactic Responses of Sensitized Animals 

The anaphylactic response of actively sensitized 
guinea pigs appears to provide the most rapid, spe- 
cific, and sensitive method for the detection of air- 
borne ricin or ricin dusts that have settled on sur- 
faces.®’^^ The animals must be watched, however, 
and the possibility of desensitization guarded 
against.®’^®" Passive sensitization was earlier em- 
ployed by British investigators 33 , 40,41 active im- 
munization has the advantages of inducing much 
more prolonged sensitization and, probably, greater 

« The sensitivity claimed for the hemagglutination reac- 
tion in reference 27 appears to be in error. 


sensitivity.® The rapidity and sensitivity of 
the reactions was demonstrated by tests in which 
characteristic responses were evoked within 1-3 min- 
utes after exposure to ricin dust at the lowest nominal 
concentrations tested, 0.03 Mg ricin nitrogen per 
liter.® This concentration was in the order of 
one- thousandth the 10-minute LC50 for mice. 

Anaphylactic reactions of guinea pigs are known 
to be highly specific. In the case of the studies with 
ricin, however, there has been debate, not yet re- 
solved, as to whether the reactions are due to sensi- 
tivity to the toxin itself or to contaminating castor 
bean allergen. The evidence that guinea pigs can be 
sensitized to ricin itself, irrespective of the possibility 
that hypersensitivity to allergen may also occur, may 
be summarized as follows: 

1. Guinea pigs passively sensitized by intravenous 
injections of rabbit antiserum to a fraction (Bl), 
which contained in relatively purified form most of 
the toxin in pilot plant ricin, were subsequently in- 
jected with fraction Bl and with fraction B3, a 
gummy fraction presumably containing much castor 
bean allergen but virtually free of ricin itself. Injec- 
tion of fraction Bl uniformly produced fatal ana- 
phylactic shock, whereas injection of fraction B3 
produced much less severe reactions. The animals 
which received fraction B3 were fatally or severely 
shocked by subsequent injections of Bl.®-^®*" 

2. All guinea pigs that had been immunized by 
injections of ten times recrystallized ricin, of pilot 
plant ricin, or of alum-precipitated ricin toxoid 
showed anaphylactic responses when injected intra- 
venously with crystalline ricin or when exposed to 
airborne pilot plant or crystalline ricin at relatively 
low concentrations.® 

3. Guinea pigs injected with ricin develop con- 
siderable immunity to the toxic effects of ricin (Sec- 
tion 12.4.3). In general, immunity in guinea pigs goes 
hand in hand with hypersensitivity. 

Since the completion of this work, Canadian in- 
vestigators ®® have reported failure of attempts to 
elicit anaphylactic responses in guinea pigs sensitized 
with crystalline ricin and exposed to airborne pilot 
plant or crystalline ricin. Animals immunized with 
pilot plant ricin showed weak responses. On the 
other hand, animals given a single injection of castor 
bean allergen reacted vigorously to crystalline 
ricin as well as to pilot plant ricin in low concentra- 
tions. These data, considered in conjunction with 
supplementary results obtained by the use of the 
Schultz-Dale technique, led to the conclusions that 


SECRET 


198 


RICIN 


the sensitization was to allergen rather than to toxin, 
and that allergen is present in crystalline ricin. Addi- 
tional evidence that a small amount of allergen is 
present even in many times recrystallized ricin has 
since been presented. 

Further work is required to clarify the apparent 
discrepancies. In any event, it is evident that guinea 
pigs can be prepared in such a way as to render them 
highly susceptible to anaphylactic, shock upon ex- 
posure to very low concentrations of all known ricin 
preparations. 

The impracticability of employing the reactions of 
animals other than dogs as routine methods of de- 
tection in warfare has often been emphasized. How- 
ever, general considerations as well as the results ob- 
tained during field trials with ricin would indicate 
that sensitized guinea pigs could be of great value in 
the hands of special officers assigned the duty of 
checking upon the possible use of protein toxins by 
an enemy. 

12.5 ASSAYS 

It was early recognized that the toxicity of castor 
beans was associated with the water-soluble, heat- 
coagulable protein of the beans.®^ ®® The presumption 
was that the toxicity was the unique property of a 
single protein component, and this hypothetical com- 
ponent was designated ricin. In 1943, a crystalline 
protein was isolated from extracts of castor beans.^-^^ 
Its toxicity was reproducible and was about twice as 
great as that of the most active amorphous product 
available. This result greatly strengthened the 
presumption that there is present in castor beans a 
single toxic protein component. However, although 
the crystalline product has met some, it has not met 
all, of the criteria of molecular homogeneity which 
are required of a single protein.^’^-^^ The possibility 
cannot yet be rigorously excluded that the toxin is a 
complex whose components may, some day, be sepa- 
rated from one another and may then be found to be 
active only in association with one another. As long 
as this possibility remains, the only assay of the toxin 
of castor bean preparations to which no objection can 
be raised is an estimation of the toxicity under ap- 
proved experimental conditions. Theoretically, the 
measurement of any physical, chemical, or biological 
property which has been shown to be quantitatively 
related to the toxicity should serve as an assay. Un- 
fortunately, the demonstration of the existence of 

^ By R. Keith Cannan. 


such a relation cannot be complete until the pure 
toxin has been isolated and fully characterized. A 
variety of properties of extracts of castor beans have 
been proposed as bases for assay and these will be 
reviewed briefly. The problem of bioassay will, how- 
ever, be considered first and in fuller detail. 

12.5.1 Bioassay 

All vertebrates that have been tested are suscep- 
tible to ricin (see Section 12.3). Few observations 
have been made on invertebrates. It has been re- 
ported ® that the motility of certain species of pro- 
tozoa is arrested by the addition of ricin to the 
medium, but it has not been established that the po- 
tencies of a series of preparations of ricin are propor- 
tional to their toxicities. Difficulties in controlling 
the action on the protozoa led to abandonment of 
the attempt to use these organisms as a means of 
assay. 

Ricin acts slowly on vertebrates. With minimum 
lethal doses, animals seldom die in less than 5 or 6 
days, and may survive for weeks. Assays based upon 
the estimation of median lethal doses are, therefore, 
protracted and require an arbitrary choice of obser- 
vation period. They also require large numbers of 
animals for statistical validity because of incidental 
variables such as casual infections. Where many 
assays must be carried out, there are obvious advan- 
tages in the adoption of a method which gives quick 
results and is economical of animals. 

The value of establishing a relation between the 
dose of ricin and the survival time in a given species 
as a basis of a method of assay was urged in 1918.^^ 
In this country the problem has been investigated 
in three different laboratories.®’®’^®-®^ Work was also 
done in Canada and in England.®®- ®^ The mouse 
has been the favored animal, being preferred to the 
rat.'^^ Several homozygous strains have been used,®-® 
the most popular one in the United States being the 
CFl strain of white mice developed by Carworth 
Farms, New City, Rockland County, New York.®’®-^® 

A method of assay based upon 24-hour mortalities 
has been adopted. Groups of five or preferably ten 
mice weighing 20-25 g are injected with a series of 
graded doses by the intraperitoneal route. The indi- 
vidual survival times of the animals are recorded and 
the mean survival time for each dose is derived. By 
interpolation in an accepted dose-survival time rela- 
tionship, a value for the dose corresponding to a 
mean survival time of 24 hours is, then, obtained for 
each experimental dose. This 24-hour lethal dose has 


SECRET 


ASSAY 


199 


been designated the toxicity unit [TU]. Because of 
the skewness of the distribution of survival times, 
one investigator ® prefers to convert each individual 
death time in a group to a TU and to average these 
to give the TU for the group. 

It has been customary to express the TU in micro- 
grams of the preparation per 20-g mouse though it is 
sometimes more useful to express it in terms of the 
total nitrogen or the coagulable nitrogen present in 
the preparation. The desirability of making a simul- 
taneous assay of a standard product has been empha- 
sized by all laboratories concerned with the evalu- 
ation of ricin preparations.^-®-^^ When this is done, 
one may then readily express the toxicity of an un- 
known preparation in terms of the per cent of the 
standard which it contains. Crystalline ricin is the 
logical reference standard. 

No difference in susceptibility to ricin of the two 
sexes of the CFl strain of mice has been detected.® 
In the cases of two other strains, small differences 
have been recorded.® Lean mice seem to be more 
resistant than fat mice of the same weight.® This 
is probably because a greater proportion of the body 
weight of the lean animals is active tissue. Studies of 
the effects of diet ® also have led to the conclusion 
that the toxicity is a function of the ratio of active 
tissue to body weight. Mice to be used for assay 
should be free from parasites. The susceptibility of 
young mice is found to be greater when the environ- 
mental temperature is elevated and is reduced at low 
temperatures.® This is presumably due to corre- 
sponding changes in body temperature. Frogs are 
also sensitive to ricin only at elevated temperatures.®® 
In the conduct of assays with mice, the temperature 
at which the mice are kept should be controlled. The 
preferred temperature has been close to 25 C. 

In one laboratory,® automatic devices for the con- 
trol of temperature, the injection of the animals, and 
the recording of individual death times have been 
employed with the object of rendering the conditions 
of assay as uniform as possible. 

If the preparation of ricin is very active, it must be 
diluted to a concentration of 10-50 mg per liter be- 
fore injection. The danger has been emphasized ® of 
losses by adsorption on the walls of the vessels in 
which the solution has been prepared. Adsorption is 
said to be significant even when paraffin-coated 
vessels are used. To reduce this error, a solution of 
0.3 per cent egg albumin has been used as the diluent 
on the principle that the excess of inert protein will 
inhibit the adsorption of the toxin.® Shorter sur- 


vival times are observed when this procedure is 
adopted,®’®’^® but there has been debate as to whether 
this was due to the suppression of adsorption or was 
the result of a synergistic action of the egg albumin. 
The modified technique has not found general ac- 
ceptance.®’^® When a simultaneous assay of crystal- 
line ricin is made and the result is expressed as the 
per cent of crystalline ricin in the product, it is prob- 
ably immaterial whether water or 0.3 per cent egg 
albumin is used as the solvent. On the other hand, 
toxicity unit values derived from assays of egg al- 
bumin solutions of ricin are consistently smaller 
than those of aqueous solutions and are not directly 
comparable with them. 

The Dose-Survival Time Curve for Mice 

For a given route of injection, this curve approxi- 
mates a rectangular hyperbola of the type repre- 
sented by the relation: ®’®’^® 

(D - Dm) 

{t - <„) 

where D is the observed dose, t is the observed sur- 
vival time, and /c is a constant characteristic of the 
preparation of ricin. Dm and tm are constants having 
the qualities of an extrapolated minimum lethal dose 
and an extrapolated minimum survival time respec- 
tively. Over a wide range of lethal doses a single pair 
of values of Dm and tm fits the experimental observa- 
tions only very roughly. Over restricted ranges of 
survival times, however, values of the constants can 
be so chosen as to fit the data quite satisfactorily.® 
For short survival times. Dm is small relative to D 
and may be ignored. Then, since the toxicity unit is 
the value of D when i = 24 hours, the above equa- 
tion can be rewritten in the form: 


This assumes that tm is independent of the nature of 
the material which is being assayed. If this assump- 
tion is not correct (and it has been implicitly ques- 
tioned) ® the assay of an unknown product by in- 
terpolation in a standard curve would be subject to 
error. However, extensive observations ® ’^® have indi- 
cated that the use of tm = 13 hours satisfies the in- 
traperitoneal data for both crystalline ricin and 
standard ricin over a range of survival times of about 
18 to 30 hours. These laboratories have, accordingly, 
adopted the following equation for general use: 


SECRET 


200 


RICIN 


TU _ 11 

13) ’ 

In order that the uncertainty of interpolation should 
be minimized, it is recommended that values of TU 
should be computed only from mean survival times 
falling within the limits of 21 and 28 hours. 

A summary of the data of one laboratory ® on 
crystalline ricin and standard ricin is given in Table 7. 
In Table 8 will be found a comparison of the results 

Table 7. Summary of a series of assays of crystalline 
ricin and of standard ricin carried out at intervals over a 
period of 13 months.® The CFl strain of mice was used. 
Solutions were prepared and diluted with water. 



Crystalline ricin 

Standard ricin 


Male 

Female 

Male 

Female 

Total number of a.ssays 
Mean toxicity unit 

23 

22 

13 

12 

tig of material 
per 20-g mouse 

2.00 

2.04 

6.96 

7.04 

Standard deviation 

0.21 

0.175 

0.79 

0.72 


Table 8. Dose-survival time relations for different routes 
of injection. The CFl strain of mice was used. Solu- 
tions were prepared in water and injected in a volume 
equal to 1 per cent of the body weight. 

Standard equation: D{t — tm) = k. 



Intravenous 

Intraperitoneal 

Subcutaneous 

k (Mg-hours) 

8.6 

23 

50 

tm (hours) 

11 

13 

16 

TU Mg/20 g 

0.66 

2.1 

6.3 

LDso Mg/kg 

2.2 

10.4 

22.1 


of intravenous, intraperitoneal, and subcutaneous 
injections.® The method of intravenous injection is 
technically too difficult for routine assays. All in- 
vestigators have agreed that intraperitoneal injec- 
tions yield more precise and reproducible results than 
do those by the subcutaneous route. Subcutaneous 
toxicities have been found to vary to a remarkable 
degree with the concentration of the solution which 
is injected.® 

12.5.2 Alternative Methods of Assay 
A variety of properties of ricin preparations have 
been proposed as bases for assay. These include the 
antigenic properties, the hemagglutinating potency, 
and various enzymic activities which have been 
found in crude preparations of ricin. The weight of 
evidence is that none of these are specific for the 
active toxin. Some of them are valuable for the com- 
parison of limited types of preparation, but must be 
supplemented by bioassays in critical situations. 


The Quantitative Precipitin Method ^ 

Antiserums prepared by the injection of crystalline 
ricin have been found to precipitate from extracts of 
castor beans, and amorphous preparations generally, 
not only the toxin, but a non toxic protein.^ Since 
this material is antigenically indistinguishable from 
the toxin, it may be called a natural toxoid. In the 
preparations that have been tested, the ratio of toxin 
to toxoid has varied from 1/1 to 2/1. Only by the 
process of crystallization has a separation of the two 
antigenic components been accomplished. If this 
limitation of the method is borne in mind, the pre- 
cipitin technique (see Section 12.4) is a valuable 
method of assay. It requires only a few micrograms 
of purified material and gives a positive result within 
a short time. 

Hemagglutination 

There is a wealth of evidence that the hemagglu- 
tinating activities of ricin preparations do not parallel 
their toxicities.^’^’^^-^^’^'^ Crystalline ricin has, for ex- 
ample, only about 20 per cent of the agglutinating 
power of amorphous preparations which are consid- 
erably less toxic. The method can, therefore, have 
only limited use. 

A method of assay based on hemagglutination 
(see Section 12.4) has been proposed for use in the 
field.22.23.26 Agglutination tests are rapid and require 
only small samples of material. However, the cus- 
tomary method of evaluating the agglutinating 
potency of a sample is only coarsely quantitative 
and depends on subjective discrimination by the ob- 
server. An attempt to increase the objectiveness and 
precision of the method has been described. 

Enzymic Activity 

The observation that crystalline ricin does not ex- 
hibit the esterase, phosphatase, and lipase activities 
of crude preparations eliminates these properties as 
means of assay.® It has recently been reported 
that ricin preparations hydrolyze adenosine triphos- 
phate. If it should be established that this activity is 
proportional to the toxicity in a representative series 
of preparations, a valuable alternative to bioassay 
may become available. 

Chemical Methods 

No chemical property of the toxin is known which 
distinguishes it from other heat-coagulable water- 
soluble proteins of the bean. However, water ex- 
tracts from castor bean contain little coagulable pro- 


SECRET 


EVALUATION AS A WAR GAS 


201 


tein other than the toxin and the toxoid. In such 
extracts, an estimation of the heat-denaturable pro- 
tein gives a result only slightly greater than the esti- 
mation of the protein precipitated by antiserum. 

In extracts prepared with salt solutions, on the other 
hand, a large additional amount of coagulable pro- 
tein is present. Fortunately this is denatured at 
or below pH 4. If such extracts are acidified and 
filtered, the soluble coagulable protein which remains 
corresponds closely to the sum of the toxin and tox- 
oid. The heat-coagulable protein has usually been 
estimated as the difference between the soluble pro- 
tein before and after boiling for 15 minutes to 1 hour 
at 100 C. Any acceptable method of protein determi- 
nation may be used which is adapted to the amount 
of protein present. 

12.5.3 Field Detection and Assay 

For the rapid detection of airborne ricin, the sensi- 
tized guinea pig is undoubtedly the most sensitive 
and specific (see Section 12.4). The maintenance 
and care of sensitized animals in the field, however, 
present many difficulties. Moreover, there is some 
question whether the anaphylactic reaction is elicited 
by the toxin or by a so-called allergen which may be 
separated from it.^’^^ 

Any other method of detection or assay requires 
the collection of samples adequate in amount for the 
test which is to be performed. Certain color tests have 
been proposed and are both sensitive and rapid. ^ In 
so far as they are simply tests for protein or for the 
carbohydrate commonly associated with protein, 
they are entirely nonspecific and are of value only in 
indicating the possible presence of ricin. More spe- 
cific, but less suited to field work, are the hemag- 
glutination and precipitin tests. Some limitations of 
the former have been mentioned. The precipitin re- 
action is decidedly more specific and more accurate. 
It has, however, been pointed out that the heavy 
metals present in some smokes will give nonspecific 
precipitates with serum proteins. Neither test gives 
an immediate response. An assay of toxicity is, of 
course, the most dilatory of all. 

It may be appropriate, in conclusion, to remind 
the reader that the hazard of exposure to a non-vola- 
tile airborne toxin cannot be evaluated simply from 
the time of exposure and the concentration of toxic 
material in the cloud. The inhalation toxicity is de- 
termined in large measure by the particle size distri- 
bution in the cloud. The relation of particle size to 
toxicity is discussed in Section 12.3 and in Chap- 


ter 15, where methods of evaluating the particle si^e 
distribution in a cloud are reviewed. In contemporary 
field trials with standard ricin, it was found profit- 
able to assay the cloud not only for toxicity and for 
particle size but also for total protein and for heat- 
coagulable protein. The two latter estimations pro- 
vided useful information on the extent to which the 
method of dispersal resulted in detoxification and 
denaturation of the material with which the muni- 
tions had been charged. The results of field trials are 
reviewed in Section 12.6. 

12.6 EVALUATION AS A WAR GAS^ 

The performance of field trials on munitions 
charged ricin and the interpretation of the results of 
these trials in terms of evaluation of the agent as a 
war gas rest in large part on the laboratory researches 
in the United States, Canada, and Great Britain on 
particulate sampling and bioassay (Chapter 15). 

The most significant criterion for effectiveness of 
ricin in the field was bioassay by animals exposed to 
the particulate cloud. Physical measurements were 
essential to an understanding of the reasons for poor 
or good results in the several trials and as a guide for 
design of subsequent trials. Low toxicity in the field 
could be associated with many variables, including 
large particle size arising from compaction and aggre- 
gation, thermal inactivation of the sensitive protein 
agent, inefficient munition functioning, and meteoro- 
logical conditions. The field trials also rested on the 
prior development of pilot plant methods for the 
preparation of finely divided ricin (Section 12.2). 

12.6.1 Relative Efficiency of Dispersion 
by Different Munitions 

The principal types of munitions and chargings 
which have been studied for the dispersion of ricin 
are the following: 

1. High explosive-chemical bombs charged with a 
suspension of ricin in carbon tetrachloride. Bombs of 
this type, with steel casings and axial bursters, were 
employed in the British experiments carried out in 
1941 and in the recent Canadian trials.^® Muni- 
tions of this type retain to a significant degree the 
effectiveness of ordinary HE fragmentation bombs. 

2. Light-case metal bombs charged with dry ricin. 
The Canadian 4 lb L.C. bomb was a metal can hold- 
ing about 550 g of ricin and fitted with a small burster 

‘ By Stanford Moore. 


SECRET 


202 


RICIN 


(e.g., 20 g of nitroguanidine and 70 g of sodium bi- 
carbonate). 

3. Base ejection bombs charged with dry ricin. 
The U.S. M-74 10-lb tail ejection incendiary bomb 
w^as modified for use with about 385 g of dry ricin.^^-^s 

4. Gas ejection bombs charged with dry ricin. 
NDRC Division 10 carried out developmental work 
on a two-compartment bomb holding liquid carbon 
dioxide or compressed air in one compartment, which 
on functioning ejected the particulate charging from 
the second compartment. 

5. Plastic and glass bombs charged with a suspen- 
sion of ricin in carbon tetrachloride. Experimental 
munitions of this type developed by NDRC Divi- 
sion 10 were similar to (1) above but with plastic or 
glass casings instead of steel. 

The lines of investigation on dispersion of ricin 
from the various types of bombs at the several field 
experimental stations have led to the same general 
conclusions. The results indicate that high explosive- 
chemical bombs charged with a 35 per cent suspen- 
sion of ricin in carbon tetrachloride are superior to 
the dry powder munitions in their ability to put up 
a cloud in wRich the volume mass median diameter 
is sufficiently small to pass the nasal barrier.^^-^*-®®’ 
37,45,46 xhis conclusion confirms the earlier analysis 
of the problem made by British investigators in 
1941 on the basis of a less complete series of 
experiments. 

In the field trials plastic bombs have given results 
comparable wdth those obtained with steel bombs 
but the British 4-lb HE/Chem Type F Mk I steel 
bomb, as used in the later Suffield trials, possessed 
the advantages of availability in standard design and 
durability in transport. 

The lower dispersion efficiency of the munitions 
charged dry powdered ricin was largely the result of 
the formation of aggregates in the particulate 
clouds. Comparisons were based on parallel tests 
employing a given sample of powdered ricin set up 
both in the dry and suspension forms. In trials with 
dry samples, aggregation of the initial particles of 
the ricin charging to yield a cloud of larger mass 
median diameter was increased by increase in the 
moisture content of the charging or in the relative 
humidity of the atmosphere .22 

In the 1941 British trials it was concluded that 
bombs filled w4th ricin suspended in carbon tetra- 
chloride were at least three times as effective as simi- 
lar bombs filled with a solution of ricin in water. In 
more recent tests with plastic bombs the solutions in 


water were also found to be less stable to detonation 
than suspensions in carbon tetrachloride. The 
munitions were functioned in a stainless-steel ex- 
plosion chamber at the NDRC University of Chicago 
Toxicity Laboratory and a material balance deter- 
mined. No measurable denaturation was observed in 
the case of the suspensions in carbon tetrachloride, 
whereas a 40 per cent loss in toxicity occurred with 
the aqueous ricin solutions. Chamber trials on the 
plastic munitions were also carried out at the Divi- 
sion 10 NDRC Munitions Development Labora- 
tory.^ 

12.6.2 Comparison with Bombs Charged 
Phosgene 

On the basis of the early trials with suspensions of 
ricin in carbon tetrachloride the British investigators 
concluded in 1941 that bombs filled with ricin 
were about as effective as phosgene bombs of the 
same size. With improvements made in the pilot 
plant manufacture of dispersible ricin since that 
date, and progress in the testing of munitions, the 
relative effectiveness of ricin has been increased to a 
position well above that of phosgene. The compara- 
tive data have been analyzed by the Suffield Experi- 
mental Station.^® From calculations of the dosage 
contours from the field trial data the munition ex- 
penditures required for 80 per cent coverage of a 
target area with a ricin dosage of at least 100 mg/ 
min/m^ have been calculated. The L{Ct)^Q of ricin 
for man is not known. The results of the field experi- 
ments indicate that for goats in the field the L(C0 50 
of the present pilot plant samples of ricin dispersed 
by the 4-lb HE/Chem Type F bomb is about 100 
mg/min/ml For the present calculations it is assumed 
that this value holds for man. Employing the meth- 
ods of calculation applied to the test data on phos- 
gene ^2 it is estimated that for 500-lb clusters of 
Type F bombs an expenditure of 1.2 clusters (43 lb 
of ricin) per 100x100 yard square would cover 
about 80 per cent of the target area with an L{Ct)^Q 
dosage on open terrain (neutral temperature gradi- 
ent; wind speed less than 12 mph). For 500-lb bombs 
charged phosgene under the same conditions the 
estimated expenditure is 8 bombs (1,600 lb of phos- 
gene) per 100x100 yard square for coverage by a 
dosage of 3,200 mg/min/m^ within 30 seconds or 
4 bombs for coverage within 2 minutes. The com- 
parison is based on tests with a batch of spray-dried 

^ These are reviewed in the Summary Technical Report of 
Division 10. 


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EVALUATION AS A WAR GAS 


203 


air-ground ricin with a volume median diameter of 

3.3 n which yielded clouds of volume mass median 
diameter of about 15 jx. 

From this it is concluded that ricin appears to be 
at least seven times as effective as phosgene on the 
basis of aircraft stowage when the comparison is 
based on a 30-second dosage of phosgene. If the 
L{Ct)f,Q for phosgene is considered to be high by even 
a factor of two there would still be a margin in favor 
of ricin. Since ricin in carbon tetrachloride gives no 
detectable odor, the comparison on the basis of a 
30-second dosage is suggested as the fairest compari- 
son. On the basis of weight of active agent employed, 
rather than the weight of munition, ricin has a superi- 
ority over phosgene of 40 to 1 from these data.'^® 

12.6.3 Ricin as a War Gas 

Ricin is an odorless powder capable of being dis- 
persed as a particulate or dust cloud. The absence of 
odor and the complexity of the consequent detection 
problem in the field would render ricin more insidious 
than any standard U. S. or British chemical war- 
fare agent. Comparison with the German Trilons 
(Chapter 9) would present a closer differentiation 
problem. The physiological effects of ricin are de- 
layed. Lung injury, similar in character to that pro- 
duced by phosgene, can lead to deaths at from one 
to several days after exposure. Ricin can be dispersed 
in munitions not readily distinguishable from stand- 
ard HE bombs. 

For detection in the field attention has been given 
to hemagglutination tests and to the use of ricin- 
sensitized guinea pigs (Section 12.4). These methods 
are intrinsically more difficult in practice than the 


simple means for detecting such agents as mustard 
gas or phosgene by odor or chemical tests. The U. S. 
and British gas masks, when well adjusted, give 
complete protection against any dosage of ricin likely 
to be produced in the field. The immunization of 
troops against ricin and serum therapy present diffi- 
culties, as outlined in Section 12.4. 

From the few tests on the persistence of ricin in 
the field it has been concluded that the major part 
of the agent is rapidly dissipated in the particulate 
cloud. Only in the area immediately around the point 
of burst was ground contamination sufficient to be 
measurable. In tests in which sensitized guinea pigs 
were allowed to run through the brush in this area a 
possible hazard was detectable for about 3 days in 
dry weather.22 

As a result of the progress made during World 
War II on the preparation and dispersion of ricin it 
must be considered that in all-out chemical warfare 
it is possible that ricin could be employed in a prac- 
tical role in chemical munitions. Supply and manu- 
facture would place a ceiling on the scale of use but 
would not prevent the accumulation of significant 
quantities of this agent. It has been estimated that 
the cost of production of dispersible ricin on a large 
scale would be approximately $13 per pound (Sec- 
tion 12.2). 

In the course of the research during World War II 
the work on ricin has served to advance the knowl- 
edge on the general problem of particulate disper- 
sion. In some respects ricin has served as a model 
substance for work on the dispersion of agents of 
similar chemical and physical properties in the re- 
lated research in the field of bacteriological warfare. 


SECRET 


Chapter 13 

AROMATIC CARBAMATES 

By Arthur C. Cope 


13.1 INTRODUCTION 

B eginning in 1943 under the auspices of the Na- 
tional Defense Research Committee [NDRC], 
search for a superior nonvolatile toxic agent was un- 
dertaken by several cooperating laboratories. Cri- 
teria for the agent sought were extreme toxicity on 
subcutaneous injection, rapid lethal action, ready 
availability through practical synthesis or otherwise, 
and sufficient stability for military use and storage. 

A survey of the open literature and information 
currently available concerning the toxicity of chem- 
ical warfare agents guided the search. Among the 
more toxic classes of substances known, botulinus 
toxin, other bacterial toxins, and potent plant toxal- 
bumins (particularly ricin) were considered unsuit- 
able because of slowness of their toxic action, 
immunological characteristics, and in some cases in- 
adequate sources of material for possible use on a 
considerable scale. 

The alkaloids physostigmine and aconitine w^ere 
high on the list of toxic substances. 


CHsNHGOOr 


CHs Ahs 
Physostigmine 


Aconitine is the more toxic of the two, but its com- 
plete structure is unknown, and search for a toxic 
agent among simpler related compounds is unprom- 
ising because minor structural modification of the 
toxic aconite alkaloids often destroys their toxicity. 
On the contrary, many synthetic N-alkylcarbamates 
related to physostigmine are highly toxic, and search 
for a superior agent in this class appeared more 
promising. For this reason, and after failure to ob- 
tain highly toxic compounds in several other classes, 
the investigation soon turned to a thorough explora- 
tion of the carbamates. Similar studies were con- 
ducted at an earlier date in England by R. D. Ha- 
worth and his associates, and in Canada by Leo 
Marion and others. The following investigations of 
carbamates reported in the open literature preceded 
all the classified work. 


After establishment of the structure of physostig- 
mine by Stedman and Barger,^^ a number of syn- 
thetic analogs were prepared by Stedman. Several 
of his papers describe the synthesis and mi- 
otic properties of such analogs, but contain no toxi- 
cological information. White and Stedman report 
a detailed pharmacological study of miotine, the syn- 
thetic miotic of choice from the group, including 
toxicity data for this substance and three related 
carbamates. Aeschlimann and Reinert report 
toxicity and other pharmacological data for physo- 
stigmine and 44 related synthetic carbamates, many 
of which had been prepared earlier by Stedman. 
Stevens and Beutel also have investigated physo- 
stigmine substitutes, and report chemical and toxic- 
ity data for 27 related carbamates. The toxicity data 
for such compounds are recorded in the open liter- 
ature.^^ 

As a result of the classified British and Canadian 
work, TL 1071 (British code T-1708) was the lead- 
ing candidate in the carbamate group. The com- 
pounds TL 1217 and TL 1299 proved to be the 
agents of choice on the basis of the NDRC work. 


I^OCONHCHs 

N(C2H5)2CHJ 
TL 1217 


iJjOCONHCHs 

N(C2H5)2CH3C1 
TL 1299 


CH3 

'^OCONHCHs 



Additional compounds that received more or less 
detailed study were : 


PCONHCH 3 


CH3 

'^OCONHCHs 


V 

N(C2H5)2CH3X 

TL 1217; X = I 
TL 1299; X = Cl 
TL 1317; X = CH 3 SO 4 


CH- 




V 

N(CH3)3X 

TL 1071; x = I 
TL 1236; X = Cl 
TL 1185; X = CH 3 SO 4 
TL 1186; X = HSO 4 


OCONHCH 3 


V 

N(CH3)3X 


TL 1216; X = I 
TL 1453; X = Cl 
TL 1188; X = CH 3 SO 4 


204 


SECRET 


SYNTHESIS 


205 


O OCON(CH3)2 


CH(CH3)2 


A' 

x(ch3)3nII J 


IOCONHCH 3 


CH(CH3)2 


TL 599: X = I TL 1327; X = I 

TL 1443; X = Cl TL 1345; X = Cl 

In the following pages work on the carbamates 
which might be of some practical importance as toxic 
agents is summarized. Investigations which led to 
selection of leading candidates are mentioned briefly. 


13.2 SYNTHESIS 


13.2.1 m-Diethylaminophenyl-N -methylcar- 
bamate methiodide (TL 1217) 


The most practical preparation of TL 1217 is the 
following sequence: 

CH 3 NC 0 


jj^OH CHsNCO^ j|^( 


1 OCONHCH 3 CH 3 I 


N(C2H5)2 


N(C2H5)2 


^|j^OCONHCH3 

N(C2H5)2CH3l 


This process was operated successfully on a pilot 
plant scale. Approximately 360 lb of methyl isocya- 
nate were prepared by reaction of methylamine and 
phosgene in the vapor phase to give methyl car- 
bamyl chloride, which was converted to methyl 
isocyanate by treatment with pyridine in toluene. 
The average yield was 81 per cent. m-Diethylamino- 
phenol (a commercial dye intermediate) dissolved 
in dry benzene was refluxed with an excess of methyl 
isocyanate for several hours. m-Diethylaminophenyl- 
N-methylcarbamate was isolated in yields of over 
80 per cent by evaporating the solvent under reduced 
pressure, filtering, washing, and drying. TL 1217 was 
prepared by reaction of m-diethylaminophenyl-N- 
methylcarbamate with methyl iodide in acetone un- 
der reflux. After addition of ethyl acetate, the prod- 
uct was recovered by filtration in yields of 79 to 
86 per cent. The product so obtained was of high 
purity, as verified by elementary analyses, use of a 
special analytical procedure involving hydrolysis and 
determination of carbon dioxide and methylamine,^^ 
and toxicity tests. 

Essentially this same procedure had been used 
earlier for the preparation of TL 1217 on a laboratory 
scale. This compound is among the group de- 
scribed by Aeschlimann and Reinert and by R. D. 
Haworth. 23 Prior to development of a practical syn- 
thesis of methyl isocyanate, m-diethylaminophenyl- 
N-methylcarbamate was prepared on a large labora- 
tory scale in yields of 74-86 per cent by reaction of 
m-diethylaminophenol with phosgene in the presence 


of diethylaniline, followed by reaction with methyl- 
ami ne. 2-3- This procedure was developed from a 
similar method used by Marion. 29-32 

13.2 .2 m-Dieth ylaminophenyl-N -methyl- 
carbamate methochloride (TL 1299) 

The most practical preparation of TL 1299 is the 
following: 



N(C2H5)2 N(C2H6)2CH3C1 N(C2H5)2CH3C1 

This process was operated successfully or a pilot 
plant scale. Redistilled m-diethylaminophenol was 
treated with an excess of methyl chloride in an auto- 
clave at 100 C. After cooling and evaporation of the 
excess methyl chloride, the product was purified and 
isolated in 77 per cent yield by grinding, washing, 
and drying. Yields in this step on a laboratory scale 
were 95 per cent.^^m-Diethylaminophenol methochlo- 
ride was converted to TL 1299 by reaction with 
methyl isocyanate in dimethylformamide as a solvent 
and a mixture of triethylamine and glacial acetic acid 
as a catalyst. Yields on a pilot plant scale were 91 per 
cent.^^ This process was developed to a high state of 
perfection in an intensive laboratory investigation,^^ 
in which yields of 94-97 per cent and 90-92 per cent 
in the two steps were obtained, or 86-90 per cent 
overall. A useful laboratory synthesis of methyl iso- 
cyanate from methylamine and phosgene also was 
developed in this work,^^ and was used until it was 
superseded by the pilot plant process for this essen- 
tial intermediate. 

Prior to development of the above process, TL 
1299 was prepared b}^ a different procedure. m-Di- 
ethylaminophenyl-N-methylcarbamate was prepared 
first from m-diethylaminophenol by the phosgene- 
methylamine procedure, with diethylaniline as the 
acid acceptor (yield 78 per cent) . 2 -3 This product 
was converted to the methosulfate salt (TL 1317) 
by reaction with methyl sulfate (yield 75-79 per 
cent), and TL 1317 was converted to TL 1299 
through reaction with anhydrous calcium chloride in 
methanol containing hydrogen chloride (yield 74 per 
cent). 2 -3 Earlier TL 1299 was prepared in high yields 
from TL 1217 and silver chloride. 2 -3-^-1^ 

13.2 .3 (2-Methyl-5-dimethylaminophenyl) - 

N-metbylcarbamate methiodide (TL 1071) 

TL 1071 (British code T-1708) was commonly 
called the “Haworth compound” during the NDRC 


SECRET 


206 


AROMATIC CARBAMATES 


investigations, since it was the leading candidate 
from the British work. Details of Haworth’s method 
of preparation could not be obtained, but Canadian 
reports on the synthesis were available and served 
as a basis for further developments. 

The intermediate 2-methyl-5-dimethylaminophe- 
nol was obtained from the National Aniline Division 
of the Allied Chemical and Dye Corporation, where 
it was prepared from p-toluidine by methylation, 
sulfonation, and alkaline fusion : 



NH 2 N(CH3)2 N(CH3)2 N(CH3)2 

2-Methyl-5-dimethylaminophenol was converted into 
the N-methylcarbamate by treatment with phosgene 
in the presence of diethylaniline, followed by methyl- 
amine (yield 75-80 per cent).^'^ With methyl isocya- 
nate available,^® this intermediate could be used in 
preparation of the N-methylcarbamate, which has 
been prepared in that manner in 85 per cent yield on 
a small scale. ^ TL 1071 was prepared from the N- 
methylcarbamate and methyl iodide in acetone in 
95 per cent yield. In a Canadian pilot plant opera- 
tion, 39 lb of TL 1071 were prepared from 2-methyl- 
5-dimethylaminophenol by this process, with an 
overall yield of 39 per cent.^^ 

Other quaternary salts differing from TL 1071 only 
in the anion were prepared. Among these were the 
methosulfate, TL 1185,^^ which was hydrolyzed 
slowly with aqueous hydrochloric acid or water to 
the acid sulfate, TL 1186.^'^ The latter on treatment 
with calcium chloride yielded the methochloride, 
TL 1236. The preferred procedure for preparing this 
compound was to heat the crude methosulfate with 
an alcoholic solution of calcium chloride for 20 hours. 
Overall yields from the N-methylcarbamate were 
77-87 per cent.^'^ Treatment of the N-methylcarba- 
mate with methyl chloride also yielded TL 1236.^ 

13.2.4 (4-Methy 1 -3 -di methylaminopheny 1) - 
N-methylcarbamate methiodide (TL 1216) 

TL 1216 was prepared during the Canadian work,^’^ 
and became known during the NDRC investigations 
as the Haworth isomer. It was synthesized in Divi- 
sion 9, NDRC, from 4-methyl-3-djmethylaminophe- 
nol, which was prepared by the National Aniline 
Division of the Allied Chemical and Dye Corpora- 
tion from o-toluidine: 



NHo N(CH3)2 N(CH3)2 N(CH3)2 

Both the phosgene-methylamine procedure and 
methyl isocyanate * were used in preparing the 
N-methylcarbamate. The methiodide, TL 1216, was 
prepared from the N-methylcarbamate.^’^^ Other 
salts prepared were the methochloride * (TL 1453) 
and the methosulfate (TL 1188). Synthetic methods 
employed paralleled those described for TL 1071. 

13.2.5 (3 -Isopropyl-4-dimethylaminophenyl) - 
N, N-dimethvlcarbamate metbiodide 
'(TL 599) 

TL 599 is the most toxic of the carbamates de- 
scribed by Stevens and Beutel.^^ Its preparation on 
any scale is hindered by lack of a practical source or 
synthesis for m-isopropylphenol, the essential start- 
ing material. An investigation of eight routes to this 
compound was made,^® of which the most satisfactory 
started with benzoic acid and continued through 
methyl m-hydroxybenzoate and m-hydroxyphenyl- 
dimethylcarbinol, by way of the Grignard reagent. 
The remaining steps in the synthesis of TL 599 were 
the following 



CH(CH3)2 CH(CH3)2 CH(CH3)2 



CH(CH3)2 

Compounds in the corresponding N-monomethyl- 
carbamate series also were prepared (TL 1327, TL 
1345). 

13.2.6 Synthesis of Other Aromatic 
Carbamates for Toxicity Tests 
In addition to the carbamates described in the 
preceding sections which were the subject of rela- 
tively intensive laboratory or pilot plant investiga- 
tions, many similar compounds were prepared on a 
small scale for toxicity tests, in the search for the 
most toxic and readily synthesized agent in the 


SECRET 


TOXICOLOGY 


207 


group. The following references contain the results 
of such investigations, and an indication of the 
classes of compounds studied where that information 
can be stated concisely; otherwise they are classified 
as miscellaneous. 

Ref. 


Classes of Carbamates Described No. 

Miscellaneous; sulfur analogs 1 

Derivatives of polyhydric phenols 4 

Derivatives of 3-diethylaminophenol, 3-dime thyl- 
aminophenol, 2-methyl-5-dimethylaminophenol and 

2-methyl-5-diethylaminophenol 5 

Derivatives of 4-dimethylaminothymol and 4-dimethyl- 

aminocarvacrol 6 

Homologs and analogs of Doryl (aliphatic carbamates) 7 
Derivatives of p-aminophenol, 4-methyl-3-aminophe- 
nol, 3-methyl-4-aminophenol, 2-methyl-5-aminophe- 

nol 8 

Derivatives of 5,6,7,8-tetrahydronaphthol-l ; 3-iso- 

propyl-4-aminophenol; miscellaneous 9 

Derivatives of 3,5-dimethyl-4-aminophenol 10 

Derivatives of 3-alkyl-4-aminophenols 11 


TL 1299, the corresponding N,N-dimethylcarbamate 
methiodide (TL 1238) and methochloride (TL 1422) 13 

Derivatives of 2-methyl-5-dimethylaminophenol, 4- 
methyl-3-dimethylaminophenol , 2-methyl-5-diethyl- 


aminophenol, w-diethylaminophenol 14 

Derivatives of 3-isopropyl-4-aminophenol, 2,6-diiso- 
propyl-4-aminophenol, 2-isopropyl-5-aminophenol, 
4-isopropyl-3-aminophenol, 4-isopropyl-2-aminophe- 

nol; arsenic analogs 19 

Miscellaneous; toxicity data only on compounds pre- 
pared by R. D. Haworth 23 

Miscellaneous 24 

Derivatives of m-dimethylaminophenol 25 

Derivatives of 2-methyl-5-dimethylaminophenol ... 26 

Derivatives of 4-methyl-3-dimethylaminophenol . . 27 

Derivatives of m-diethylaminophenol 29 

Derivatives of 2,4-dimethyl-5-dimethylaminophenol . 31 

Miscellaneous 34 

Miscellaneous 43 

Miscellaneous 44 

Miscellaneous 45 

Miscellaneous 46 

Miscellaneous 47 

Miscellaneous 48 

Miscellaneous 49 

Miscellaneous 50 

Miscellaneous 51 

Miscellaneous 52 

Miscellaneous 53 

13.3 STABILITY 


The toxic aromatic carbamates of possible practi- 
cal importance are reasonably stable at 65 C, show- 
ing little decomposition after 2 months storage.^® 
The two labile groups in such compounds are the 
carbamate and quaternary salt linkages. The carbam- 
ate group is subject to thermal decomposition to 
methyl isocyanate and the corresponding phenol, 
and to hydrolysis to the phenol, methylamine, and 
carbon dioxide, or related products. The quaternary 


salt groups are subject to decomposition at elevated 
temperatures to an alkyl halide and the correspond- 
ing tertiary amine. If the carbamates are kept dry, 
they have good thermal stability. The same pre- 
caution protects them from hydrolysis. Hydrolysis is 
very rapid in alkaline solutions, and slow at an acid 
pH. As a precaution to insure stability, the carbam- 
ates may be crystallized from solvents containing 
hydrogen chloride. Alternatively, acidic stabilizers 
such as sodium acid sulfate or hydrazine dihydro- 
chloride may be added. 

A number of the more toxic carbamates were ex- 
amined for relative stability at a time when it ap- 
peared that stability might be a decisive factor in 
choice of a superior agent. The following conclusion 
was reached concerning thermal stability: variation 
in the anion of the quaternary ammonium salt re- 
sults in the following order of decreasing stability: 
methosulfate > methiodide > methochloride. Com- 
paring stabilities toward hydrolysis, two N,N-di- 
methylcarbamates were much more stable than two 
N-methylcarbamates (TL 1071 and TL 1217), which 
in turn were more stable than two N-arylcarbam- 
ates. Ultimately the two agents chosen as superior on 
the basis of toxicity and ease of manufacture (TL 
1217 and TL 1299) were determined to be sufficiently 
stable for any anticipated use. 

One factor with an important bearing on stability 
is the hygroscopic character of some of the carbam- 
ates. TL 1299 is quite hygroscopic in humid weather.^ 
TL 1217 is not, and largely for this reason became 
the agent of choice. TL 1299 could be handled satis- 
factorily if it were needed on a large scale by con- 
trolling the humidity of the rooms in which it would 
be crystallized, dried, and packaged. Whereas this 
could be done readily on a full manufacturing scale, 
on the large laboratory and pilot plant scale it was 
much simpler to employ the nonhygroscopic methi- 
odide, TL 1217. 

13.4 TOXICOLOGY 

A report has been prepared which summarizes 
much of the toxicological work done in this country, 
in Britain, and in Canada on the aromatic carbam- 
ates. Tables from this report, reprinted as Table 2 
of this chapter give toxicity data for the 319 aro- 
matic carbamates and closely related compounds 
known to have been tested. 

Aromatic carbamates prepared as part of the 
NDRC program were submitted to the University 
of Chicago Toxicity Laboratory for testing. There 


SECRET 


208 


AROMATIC CARBAMATES 


they received a TL (Toxicity Laboratory) number, 
and were tested for subcutaneous toxicity to mice. 
Two to five mice were injected subcutaneously with 
doses of 80, 40, 20, 10, 5, and 1 mg/kg of body 
weight, at dilutions such that each mouse received 
approximately 1 per cent of its body weight in a 
suitable nontoxic solvent (usually water). Any com- 
pound that killed at 1.0 mg/kg was screened further 
and LDso determinations were made for all those 
killing at less than 0.5 mg/kg. The data obtained are 
listed in Table 2 , together with similar toxicity data 
obtained elsewhere for other aromatic carbamates. 

A number of factors influencing toxicity determina- 
tions made by injection. were studied carefully for 
the more important aromatic carbamates. One of the 
most important was the animal species used in test- 
ing. The leading candidates were tested in several 
animal species, since the object of the search was to 
select an agent toxic for all species. TL 1217 proved 
to be very toxic for all species in which it was tested. 
TL 1345 is the most toxic compound tested in mice, 
but as Table 1 shows, it presents no marked superi- 

Table 1. Subcutaneous toxicities of TL 1217 and TL 

1345 for various species. 

LD 50 (mg/kg) 

0 OCONHCH 3 f| OCONHCH 3 

C 1 (CH 3 ) 3 N[I J 

N(C2H5)2CH3l CH(CH3)2 


Species 

TL 1217 

TL 1345 

Mouse 

0.129 

0.047 

Rat 

ca. 0.400 

0.103 

Guinea pig 

0.097 

ca. 0.050 

Rabbit 

ca. 0.150 

ca. 0.075 

Cat 

ca. 0.075 

ca. 0.100 

Dog 

ca. 0.075 

ca. 0.100 

Monkey 

ca. 0.200 

ca. 0.150 


ority over TL 1217 when other species are con- 
sidered. 

Other factors considered in precise toxicity de- 
terminations were the concentration of the solution 
injected; the strain, sex, body weight, and age of the 
mice used in LD 50 determinations; and the effect of 
the temperature of the environment of the assay 
animals. A number of compounds were tested by 
various routes of administration, and the following 
conclusions were reached. 

1. The carbamates tested were about twice as 
toxic intravenously as by any other route. 

2 . Subcutaneous injection was more effective than 


intraperitonea 1. (In the single comparison available 
for rats the intraperitoneal route was the more 
effective.) 

3. Carbamates are relatively ineffective when ad- 
ministered by stomach tube, 25 to 500 times as much 
material being required to kill as by injection. 

The carbamates are toxic when administered by 
inhalation as aerosols, but do not show the ex- 
traordinary toxicity in comparison with standard 
chemical warfare agents which characterizes them 
when toxicities determined by injection are com- 
pared. 

The aromatic carbamates are “quick-kill” agents 
capable of producing severe parasympathomimetic 
effects terminating in death. Death occurs rapidly, 
for example, in 5 to 20 minutes after subcutaneous 
injection in dogs. The symptoms produced are similar 
in all species which have been examined. They con- 
sist of salivation, evacuation of bowels and bladder, 
restlessness and incoordination, and fibrillary muscu- 
lar movements. Respiratory movements are -quick- 
ened and labored. Coma is accompanied or preceded 
by convulsive movements. Respiration appears to 
cease first, the heart beating, usually irregularly, for 
some moments after respiration has failed. Muscular 
twitching persists for some time after failure of res- 
piration and cardiac activity. 

The aromatic carbamates are powerful cholin- 
esterase poisons, and produce marked changes in 
the blood. Because of medical and toxicological in- 
terest in them, their physiological mechanism of 
action has received considerable study. Most of this 
work may be located through certain leading refer- 
ences.^® Atropine or atropine and pento- 
barbital administered intravenously have been rec- 
ommended as antidotes for the carbamates.^® Anti- 
dotes can be demonstrated to be useful in animals, 
but must be administered quickly (at the onset of 
symptoms) because of the very rapid toxic action of 
the carbamates. 

For references to toxicity assays on the carbamates 
in addition to the summary previously mentioned 
see the Bibliography.^^®'’'^’®’^’^®'^®-®®-®®’®^.”^®’^®'^®'®® 

13.5 RELATIONSHIP BETWEEN CHEMI- 
CAL STRUCTURE AND TOXICITY 

Relationships existing between chemical structure 
of the aromatic carbamates and their toxicity have 
been pointed out in some detail. The following prin- 
cipal conclusions can be drawn from the available 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


209 


toxicity data (figures cited refer to subcutaneous 
toxicity in mice). 

1. The most toxic compounds contain both a 
carbamate and a quaternary salt group. 

2. The carbamate group is more intimately con- 
nected with toxicity than is the quaternary salt 
group. This conclusion follows from several lines of 
evidence : 

a. The quaternary ammonium group can be re- 
placed with sulfonium or arsonium without change 
in order of magnitude of toxicity. For example: 


A 


| 0 C 0 NHCH 3 

V 

N(C2H5)2CH3l 


TL 1217 

LDio = 0.129 mg /kg 


n 


0CONHCH3 


V 

S(CH3)3S04CH3 


TL 1306 

LDw = 0.37 mg /kg 


IOCONHCH3 


As(C2H5)2CH3l 


TL 1504 

LDho = 0.5 mg /kg 


b. The 6fs-N,N-dimethylcarbamate of catechol is 
highly toxic even though it contains no basic group; 
introduction of a quaternary salt group in this com- 
pound results in diminished toxicity. 


) 0C0N(CH3)2 
0C0N(CH3)2 


TL 1015 

LDw = 1.4 mg /kg 


0 OCON(CH,)j 
0 C 0 N(CH ,)2 


TL 1155 

Toxic dose >10 mg /kg 


c. Quaternary salts derived from aminophenols 
are not very toxic, but the N-methylcarbamates de- 
rived from some of them are highly toxic. 



N(C2H5)2CH3C1 
TL 1309 

Toxic dose about 40 mg /kg 


A 


OCONHCH3 


V 

N(C2H5)2CH3C1 


TL 1299 

LDbQ = 0.09 mg /kg 


d. Structural changes in the carbamate group in 
related series of compounds may produce enormous 
changes in their toxicity. 


0 OCONHCH3 

N(CH3)3l 
TL 1216 

LDm =0.17 mg /kg 


lOCONHCHs 


s/ 

N(C2H5)2CH3l 


TL 1217 

LDao = 0.129 mg/kg 


0 SCONHCH3 

N(CH3)3l 
TL 1239 

Toxic dose > 80 mg /kg 


0 ' 


0 C 0 N(CH 3)2 


/ 

N(C2H5)2CH3l 


TL 1238 

LDio = 0.175 mg/kg 


0 


OCON 


CH2CH2 


CH2CH, 


CH2 


N(C2H6)2CH3l 
TL 1346 

Toxic dose about 1 mg/kg 


0 


OCONHC2H5 


N(C2H5)2CH3l 
TL 1481 

Toxic dose about 5 mg/kg 


iJ^OCONHCeH.. 

N(C2H5)2CH3l 
TL 1433 

Toxic dose > 80 mg /kg 


|jjj0C0NHC6H40CH3-, 

N(C2H5)2CH3l 
TL 1442 

Toxic dose > 80 mg /kg 


e. Changes in the quaternary salt group in a series 
in which the N-methylcarbamate group is kept con- 
stant produce smaller changes in toxicity. 


OCONHCH3 

A 

H^N(CH,),I 


TL 1178 

LDw) = 0.270 mg/kg 

OCONHCH3 

A 

yNCHJ 

(CjHs)^ 

TL 1217 

LDso = 0.129 mg/kg 

OCONHCH3 

A 

i)JN(CH3)2Br 

(CH2)2CH3 

TL 1434 

LDm =0.10 mg /kg 


OCONHCH3 

0 

'>!Jn(ch3)2I 

C2H6 

TL 1323 

LDbo = 0.135 mg/kg 

OCONHCH3 

CH2CH=CHs 

TL 1435 

LDba = 0.102 mg/kg 

OCONHCH3 

(Qn(CA)J 


TL 1259 

LDio = 0.23 mg /kg 


OCONHCH3 

A 

yNCH3l 

(Ahs)^ 

TL 1324 

LDm = 0.48 mg/kg 


3. In general, the N-methylcarbamates are more 
toxic than corresponding N,N-dimethylcarbamates. 
Of 20 such pairs of compounds tested, the mono- 
methylcarbamates were more toxic in 14 cases (for 
some pairs they were 10 to 40 times as toxic) ; in the 
other 6 cases they were approximately equal. No 
other substitution on the carbamate nitrogen which 
was investigated led to compounds as toxic as the 
N-methyl and N,N-dimethyl derivatives. 


SECRET 


210 


AROMATIC CARBAMATES 


4. With few exceptions, the most toxic compounds 
were those in which the N-methylcarbamate and 
quaternaiy salt groups were in the meta orienta- 
tion. 


lOCONHCHs 

In(ch3)3I 


Toxic dose 430 mg /kg 


OCONHCH 3 


N(CH3)3l 

TL 1178 

LDm = 0.27 mg /kg 



0 


IOCONHCH 3 


I(CH3)3N 


TI, 1097 

Toxic dose about 20 mg /kg 


5. Methyl substitution in the nucleus ortho or 
para to the carbamate produces no great change in 
the toxicity of m-quaternary compounds, and may 
result in slightly more toxic substances. Similar sub- 
stitution by higher alkyl groups leads to less toxic 
compounds. 


0 OCONHCH; 

N(CH3)3l 

TL 1178 


CH 3 


IOCONHCH 3 


N(CH3)3l 

TL 1071 


0 


OCONHCH 3 


N(CH3)3l 

TL 1216 


LDbo — 0.27 mg/kg LDbo = 0.111 mg/kg LDbo = 0.17 mg/kg 


6. The series with an alkyl substituent meta and 
the quaternary salt para to the carbamate group 
contains some extremely toxic compounds. In the 
most toxic homologs of this type the alkyl group 
is isopropyl. 


A 


0 OCONHCH 3 
CH(CH3)2 

TL 1327 

LDbo = 0.067 mg/kg 


O OCON(CH3)2 

CH(CH3)2 

TL 599 

LDbo = 0.085 mg /kg 


7. The toxicity of aromatic carbamates substi- 
tuted by quaternary salt groups resides in the cation. 
Of the various salts, the chlorides have been found to 
be somewhat more toxic than would be calculated on 
a molecular weight basis. Other salts with the same 
cation have toxicities proportional to their molecular 
weights. 


Table 2. Toxicities of aromatic carbamates and related compounds. 

The following tables contain the toxicity data available as of March 1945 for aromatic carbamates and closely related 
substances (319 in all). The tables are subdivided into 18 structural classes, as follows: 


I Benzene compounds with one carbamate group, and 
no quaternary ammonium group. 

II Benzene compounds with two carbamate groups and 
no other groups. 

III Benzene compounds with two carbamate groups and 

other groups. 

IV Benzene compounds with three carbamate groups and 

no other group. 

V Benzene compounds with one carbamate group and 
one quaternary ammonium group in the ortho 
position. 

VI Benzene compounds with one carbamate group and 
one quaternary ammonium group in the ortho 
position and alkyl groups. 

VII Benzene compounds with one carbamate group and 
one quaternary ammonium group in the meta 
position. 

VIII Benzene compounds with one carbamate group and 
one quaternary ammonium group in the meta 
position and other substituents. 

IX Benzene compounds with one carbamate group and 
one quaternary ammonium group in the para posi- 
tion (including thiocarbamates). 

X Benzene compounds with one carbamate group and 
one quaternary ammonium group in the para posi- 
tion and other substituents. 

XI Benzene compounds with one carbamate group and 
an alkyl side chain having a quaternary ammo- 
nium group. 

XII Benzene compounds with one carbamate group and 
two quaternary ammonium groups. 


XIII Benzene compounds with one carbamate group and 

one sulfonium or arsonium group. 

XIV Carbamates of naphthalene derivatives. 

XV Carbamates of quinoline and isoquinoline deriva- 
tives. 

XVI Carbamates of aliphatic alcohol derivatives. 

XVII Miscellaneous carbamates. 

XVIII Carbamides and carbazates. 

The tables represent a revision of a similar review issued on 
June 15, 1944,^® and follow the system of classification used in 
the earlier summary. Entries in the column headed “Code” 
have the significance noted in the Glossary. 

In the column headed “Route and Solvent” the following 
abbreviations are used: 

Sc.W. = subcutaneous injections in water. 

Sc.P. = subcutaneous injections in propylene glycol. 

Sc.O. = subcutaneous injections in olive oil. 

Sc.M. = subcutaneous injections in mineral oil. 

Sc.Imp. = subcutaneous implantation of dry solid. 

Iv.W. = intravenous injection in water. 

Im.Imp. = intramuscular implantation of dry solid. 

Ip.W. = intraperitoneal injection in water. 

Oral W. = administered by stomach tube, in water. 

pH-4 indicates that this acidity was achieved with Mcll- 
vaine’s buffer. 

Whenever the room temperature during the determination 
was recorded, it was listed immediately following the LD^q 
figure. 


SECRET 



CHEMICAL 

STRUCTURE AND TOXICITY 

211 


I. Benzene compounds with one 

carbamate group, and no quaternary ammonium group. 


Code 

Name 

Route 

and Dose 

Structure solvent Species mg/kg 

Effect 


AR-1 Carbamic acid, N-methyl- 
phenyl ester 


OCONHCH 3 Iv. Mice >50 LDso 



TL-1113 Carbamic acid, N,N-dimethyl- 
phenyl ester 


0C0N(CH3)2 Sc.M. 



Mice 

80 

0/2 


40 

0/2 


20 

0/2 


TL-1218 Carbamthiolicacid,N-methyl- 
p-tolyl ester 


TL-997 Carbamic acid, N-methyl-2- 
AR-2 nitrophenyl ester 


SCONHCH3 Sc.P. 



CH3 


OCONHCH3 Sc.Imp. 



Mice 

80 

2/2 


40 

0/2 


20 

0/2 


Mice 

80 

0/2 

Mice 

33 

LD^o 


TL-948 Carbamic acid, N-methyl-3- 
nitrophenyl ester 


OCONHCH3 Sc.Imp. 


Mice 

80 

0/2 


40 

0/2 


20 

0/2 


TL-947 Carbamic acid, N-methyl-4- 
nitrophenyl ester 


TL-980 Carbamic acid, N-methyl-2- 
hydroxy phenyl ester 


OCONHCH3 Sc.Imp. 



NO2 


OCONHCH3 Sc.Imp. 



Mice 

80 

0/2 


40 

0/2 


20 

0/2 


Mice 

80 

0/2 


40 

0/2 


20 

0/2 


TL-1016 Carbamic acid, N,N-dimethyl- 
2-hydroxyphenyl ester 


0C0N(CH3)2 Sc.W. 



Mice 

80 

0/2 


40 

0/2 


20 

0/2 


TL-979 Carbamic acid, N,N-diethyl- 
2-hydroxyphenyl ester 


0C0N(C2H3)2 Sc.Imp. 



Mice 

80 

0/2 


40 

0/2 


20 

0/2 


TL-1161 Carbamic acid, N,N-dimethyl- 
2-allyloxyphenyl ester 


TL-1 1 10 Carbamic acid, N,N-dimethyl- 
4-allyl-2-methoxyphenyl 
ester 


0C0N(CH3)2 



Sc.O. 


Sc.M. 


Mice 


Mice 


80 

40 

20 


80 

40 

20 


0/2 

0/2 

0/2 


0/2 

0/2 

0/2 


SECRET 


212 


AROMATIC CARBAMATES 


Table 2, Section I {Continued) 


Code 


Name 


Route 

and Dose 

Structure solvent Species nig/kg Effect 


TL-1 111 Carbamic acid, N,N-dimethyl- 
2-methoxy-4-propylphenyl 
ester 


0C0N(CH3)2 

OCH3 


Sc.M. 

Mice 

80 

0/2 



40 

0/2 



20 

0/2 


TL-1 116 Carbamic acid, N,N-dimethyl- 
4-allyl-2-methoxy-5-nitro- 
phenyl ester 


CH2CH2CH3 

0C0N(CH3)2 


OCH3 


Sc.M 

Mice 

80 

0/2 



40 

0/2 



20 

0/2 


O2N 


CH2CH=CH2 


TL-1015 


TL-978 


II. Benzene compounds with two carbamate groups and no other groups. 


Benzene, l,2-6is(methyl- 
carbamyloxy)- 


OCONHCH3 
I K 


OCONHCH3 


Sc.W. Mice 


Benzene, l,2-6is(dimethyl- 
carbamyloxy)- 


0C0N(CH3)2 Sc.P. Mice 

j^OCON(CH,)2 


40 

2/2 

20 

2/2 

10 

0/2 

5 

0/2 

1.4 

LDso 


TL-1 118 Benzene, l,2-6zs(diethylcar- 
bamyloxy)- 


0C0N(C2H=,)2 Sc.P 

|^0C0N(C2H,)2 


Mice 

80 

0/2 


40 

0/2 


20 

0/2 


TL-1119 Benzene, l,2-6is(N-penta- 
methylenecarbamyloxy )- 


OCONC5H10 Sc.M 

j^OCONCsHio 


Mice 

80 

0/2 


40 

0/2 


20 

0/2 


TL-1 112 Benzene, l,3-62s(dimethylcar- 
bamyloxy)- 


TL-1114 Benzene, l,4-6w(dimethylcar* 
bamyloxy)- 


TL-1348. Benzene, l,4-6zs(methylcar- 
bamyloxy)- 


0C0N(CH3)2 Sc.W. 



0C0N(CH3)2 


OCONHCH3 Sc.P. 



OCONHCH; 


Mice 

80 

0/2 


40 

0/2 


20 

0/2 


Mice 

80 

0/2 


40 

0/2 


20 

0/2 


Mice 

80 

0/2 


40 

0/2 


20 

0/2 


III. Benzene compounds with two carbamate groups and other groups. 


TL-1 117 Benzaldehyde, 3,4-6is(dimethyl- 

0C0N(CH3)2 

Sc.P. 

Mice 

80 

0/2 

carbamyloxy)- 

/\ 



40 

0/2 


f ]0C0N(CH3)2 



20 

0/2 


CHO 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


213 


Table 2, Section III {Continued) 


Code 


Name 


Route 

and Dose 

Structure solvent Species mg/kg Effect 


TL-1157 Benzyl alcohol, 3,4-6is(di- 
methylcarbamyloxy )- 


TL-1160 Dimethylamine, N-[3,4-6is(di- 
methylcarbamyloxy )benzyl3 
hydrochloride 


TL-981 Benzene, l,2-6z5(dimethyl- 
carbamyloxy)-4-nitro- 


TL-1017 Benzene, l,2-6is(dimethylcar- 
bamyloxy)-4-amino- 


TL-1155 Benzene, 4-(dimethylamino)- 
l,2-6zs(dimethylcarbamyl- 
oxy)-, methiodide 


TL-1159 Benzene, l,2-6is(dimethylcar- 
bamyloxy )-3-allyl- 


TL-1158 Benzene, l,2-6is(diJ^ethylcar- 
bamyloxy)-3-propyl- 


TLr-1162 Benzene, l,2-6ts(dimethylcar- 
bamyloxy )-4-ally 1- 


TL-1156 Benzene, l,2-6is(dimethylcar- 
bamy loxy )-4-propyl- 


TL-1086 Benzene, l,3-6ts(N-methylcar- 
bamyloxy)-2-nitro- 


0 C 0 N(CH 3)2 

|^ 0 C 0 N(CH 3)2 

CH2OH 

0 C 0 N(CH 3)2 

j^OCON(CH3)2 

^H2N(CH3)2-HC1 

0 C 0 N(CH 3)2 

j^OCON(CH3)2 

NO2 

0 C 0 N(CH 3)2 

j^OCON(CH3)2 

NH2 

0 C 0 N(CH 3)2 

j^OCON(CH3)2 

N(CH 3 ) 3 l 

0 C 0 N(CH 3)2 

O OCON(CH3)2 

CH2CH=CH2 

0 C 0 N(CH 3)2 

O OCON(CH3)2 

CH2CH2CH3 

0 C 0 N(CH 3)2 

j^OCON(CH 3)2 

CH2CH=CH2 

0 C 0 N(CH 3)2 

j^OCON(CH3)2 

CH2CH2CH3 

OCONHCH3 

0 NO2 

OCONHCH3 


Sc.W. Mice 


Sc.W. Mice 


Sc. Imp. Mice 

Sc.O. 


Sc. N/10 Mice 
Ac. 


Sc.W. Mice 


Sc.O. Mice 


Sc.O. Mice 


Sc.O. Mice 


Sc.M. Mice 


Sc.P. Mice 


10 

1/2 

5 

0/2 

1 

0/2 


10 

2/2 

5 

2/2 

1 

0/2 

0.5 

0/2 


80 

0/2 

80 

0/2 

40 

0/2 


40 

2/2 

20 

2/2 

10 

2/2 

5 

0/2 


10 

0/2 

5 

0/2 

1 

0/2 

0.5 

0/2 


10 

0/2 

5 

0/2 

1 

0/2 

0.5 

0/2 

10 

0/2 

5 

0/2 

1 

0/2 

0.5 

0/2 

10 

0/2 

5 

0/2 

1 

0/2 

0.5 

0/2 


10 

0/2 

5 

0/2 

1 

0/2 

0.5 

0/2 


40 

0/2 

20 

0/2 


SECRET 


214 


AROMATIC CARBAMATES 




Table 2, Section III {Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


TL-1129 Benzene, l,3-6is(N-methylcar- 
bamyloxy)-2-amino hydro- 
chloride 


TL-1349 Benzene, l,4-6z's(niethylcarba- 
myloxy )-2,6-dime t hyl- 


OCONHCH 3 

sNH2-HC1 

/'OCONHCH 3 

OCONHCH 3 

/ Vh 3 


Sc.W. 


Mice 


Sc.P. 


Mice 


CHaj^C 


TL-1350 Benzene, l,4-6/s(methylcarba- 
my loxy )-2-isopropy 1-5- 
methyl- 


OCONHCH 3 
OCONHCH 3 

0 CH(CH3)2 

OCONHCH 3 


Sc.P. 


Mice 


TL-1115 Benzene, l,2,3-<m(dimethyl- 
carbamyloxy)- 


IV. Benzene compounds with three carbamate groups and no other group. 

Sc.W. Mice 


0C0N(CH3)2 

O OCON(CH3)2 
0C0N(CH3)2 


V. Benzene compounds with one carbamate group and one quaternary ammonium group in the ortho position. 


TL-963 Carbamic acid, N-methyl-2- 
ami nophenyl ester hydro- 
chloride 


T-(?) Carbamic acid, N-methyl-2- 
dimethylaminophenyl ester 
methiodide 


OCONHCH 3 
jNH 2 -HCl 

OCONHCH 3 
. ]N(CH3)3l 


Sc.W. 


Mice 


Sc. 


Mice 


80 

0/2 

40 

0/2 

20 

0/2 

80 

0/2 

40 

0/2 

20 

0/2 

80 

2/2 

40 

1/2 

20 

1/2 

10 

0/2 

5 

0/2 

40 

2/2 

20 

2/2 

10 

0/2 

5 

0/2 

jho position. 

80 

0/2 

40 

0/2 

20 

0/2 

430 

LDso 


VI. Benzene compounds with one carbamate group and one quaternary ammonium 
group in the ortho position and alkyl groups. 

Sc.W. Mice 


TL-1488 Carbamic acid, N-methyl-2- 
dimet hylamino-4-isopropyl- 
phenyl ester methiodide 


SB-13 Carbamic acid, N,N-dimethyl- 
2-dimethylamino-4-methyl- 
phenyl ester hydrochloride 


lN(CH3)3l 


OCONHCH 3 

0 

CH(CH3)2 
0C0N(CH3)2 
j^N(CH3)2-HCl 


80 

40 

20 


Sc. 


Mice 


0/2 

0/2 

0/2 


Approx. 200 LDs 


CH 3 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


215 


Table 2, Section VI {Continued) 


Code 


Name 


Route 

and Dose 

Structure solvent Species mg/kg Effect 


SB-14 Carbamic acid, N,N-dimethyl- 
2-di met hylamino-4-methyl- 
phenyl ester methiodide 


SB-15 Carbamic acid, N,N-dimethyl- 
2-dimethylamino-4-ethyl- 
phenyl ester hydrochloride 


SB-16 Carbamic acid, N,N-dimethyl- 
2-dimethylamino-4-ethyl- 
phenyl ester methiodide 


SB-17 Carbamic acid, N,N-dimethyl- 
2-dimethylamino-4-isopro- 
pylphenyl ester hydrochlo- 
ride 


SB-18 Carbamic acid, N,N-dimethyl- 

2-dimethylamino-4-isopro- 
pylphenyl ester methiodide 


SB-19 Carbamic acid, N,N-dimethyl- 
2-dimethylamino-4-fer< butyl- 
phenyl ester hydrochloride 


SB-20 Carbamic acid, N,N-dimethyl- 
2-dimethylamino-4-fer< butyl- 
phenyl ester methiodide 


SB-21 Carbamic acid, N,N-dimethyl- 
2-dimethylamino-4-ieri 
amylphenyl ester hydro- 
chloride 


SB-22 Carbamic acid, N,N-dimethyl- 
2-dimethylamino-4-feri 
amylphenyl ester methi- 
odide 


0C0N(CH3)2 

j^N(CH3)3l 

CHs 

0C0N(CH3)2 

|^N(CH3)2-HC1 

C 2 H 5 

0C0N(CH3)2 

|^N(CH3)3l 

C 2 H 5 

0C0N(CH3)2 

|^N(CH3)2-HC1 

CH(CH3)2 

0C0N(CH3)2 

|^N(CH3)3l 

CH(CH3)2 

0C0N(CH3)2 

j^N(CH3)2HCl 

C(CH3)3 

0C0N(CH3)2 

j^N(CH3)3l 

C(CH3)3 

0C0N(CH3)2 

j^N(CH3)2'HCl 

C2H6C(CH3)2 

0C0N(CH3)2 

j^N(CH3)3l 

C2H5C(CH3)2 


Sc. 


Sc. 


Sc. 


Sc. 


Sc. 


Sc. 


Sc. 


Sc. 


Sc. 


Mice 2.0 LD50 


Mice 27 LDso 


Mice 1.25 LD50 


Mice >400 LD^q 


Mice 4.8 LD^o 


Mice >500 LD^o 


Mice 13.5 LD^o 


Mice >500 LD 50 


Mice 12 LD 50 


SECRET 


216 


AROMATIC CARBAMATES 


Table 2 {Continued) 

VII. Benzene compounds with one carbamate group and one quaternary ammonium group in the meta position. 


Code 


Name 


Structure 


Route 

and 

solvent 


Species 


Dose 

mg/kg 


Effect 


TL-1309 Phenol, 3-(diethylamino)- 
methochloride 


T-1122 Carbamic acid, 3-dimethyl- 
aminophenyl ester methio- 
dide 


AR-11 Carbamic acid, 3-dimethyl- 
aminophenyl ester metho- 
sulfate 


TL-946 Carbamic acid, N-methyl-3- 
aminophenyl ester hydro- 
chloride 


AR-12 Carbamic acid, N-methyl-3- 
dimethylaminophenyl ester 
hydrochloride 


OH Sc.W. Mice 

]n(C2H5)2CH3C1 
OCONH2 Sc. Mice 

]n(CH3)3I 

OCONH 2 Iv. Mice 

JN(CH3)3S04CH3 
OCONHCH 3 Sc.W. Mice 

]nH2 -HC1 

OCONHCH 3 Iv. Mice 

JN(CH3)2*HC1 


80 

40 

20 

10 

37 


80 

40 

20 


15 


2/2 

2/2 

0/2 

0/2 

LDkq 


0.7 LA, 


0/2 

0/2 

0/2 


LDgi 


T-1152 

Carbamic acid, N-methyl-3- 

OCONHCH 3 

Sc. 

Mice 

0.44 

LDgQ 


dimethylaminophenyl ester 


Sc. 

Rabbit 

0.26 



methiodide 

1 In(CH3)3I 

Sc. 

Mice 

30 


TL-1178 

Carbamic acid, N-methyl-3- 

OCONHCH 3 

Sc.W. 

Mice 

0.27 

LDso 


dimethylaminophenyl ester 

A 

Iv.W. 

Mice 

0.115 

LDso 


methiodide I 

1 1n(CH3)3I 


(See p. 219) 



TL-1226 

Carbamic acid, N-methyl-3- 

OCONHCH 3 

Sc.W. 

Mice 

0.140 

LDso 


T-1690 


AR-13 


TL-1323 

T-1194 


dimethylaminophenyl ester 
methochloride 


Carbamic acid, N-methyl-3- 
dimethylaminophenyl ester 
methochloride 


Carbamic acid, N-methyl-3- 
dimethylaminophenyl ester 
methosulfate 


Carbamic acid, N-methyl-3- 
dimethylaminophenyl ester 
ethiodide 


JN(CH3)3C1 
OCONHCH 3 

)n(CH3)3C1 
OCONHCH 3 

]n(CH3)3S04CH3 

OCONHCH 3 

jN(CH3)2C2H5l 


Iv.W. 


Sc. 


Iv. 


Sc.W. 

Sc. 

Sc. 


Mice 


Mice 


Mice 


Mice 

Mice 

Rabbit 


0.070 


0.27 


0.1 


0.135 

0.38 

0.13 


LD, 


LD, 


LDk{ 


LD50 

LDso 

LDso 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


217 


Table 2 , Section VII {Continued) 


Code 


Name 


Structure 


Route 

and 

solvent 


Species 


Dose 
mg /kg 


Effect 


AR-14 Carbamic acid, N-methyl-3- 
ethylmethylaminophenyl 
ester methobromide 


TL-1434 Carbamic acid, N-methyl-3- 
dimethylaminophenyl ester 
propyl bromide 


TL-1435 Carbamic acid, N-methyl-3- 
dimethylaminophenyl ester 
allyl bromide 


TL-1324 Carbamic acid, N-methyl-3- 
dibutylaminophenyl ester 
methiodide 


AR-15 Carbamic acid, N-methyl-3- 
diethylaminophenyl ester 
hydrochloride 


TL-1217 Carbamic acid, N-methyl-3- 
diethylaminophenyl ester 
methiodide 


T-1123 

AR-16 

TL-1299 Carbamic acid, N-methyl-3- 
Prep. 1 diethylaminophenyl ester 

Prep. 2 methochloride 

Prep, 3 
Prep. 3 

TL-1317 Carbamic acid, N-methyl-3- 
diethylaminophenyl ester 
methosulfate 


TL-1259 Carbamic acid, N-methyl-3- 
diethylaminophenyl ester 
ethiodide 


AR-31 Carbamic acid, N,N-dimethyl- 
3-dimethylaminophenyl 
ester acid tartrate 


OCONHCH 3 Iv. 

]N(CH3)2C2H5Br 

OCONHCH 3 Sc.W. 

]N(CH3)2CH2CH2CH3Br 
OCONHCH 3 Sc.W. 

)N(CH3)2CH2CH=CH2Br 
OCONHCH 3 Sc.W. 

]n(C4H9)2CH3I 

OCONHCH 3 Iv. 

JN(C2H5)2-HC1 
OCONHCH 3 

Jn(C2H5)2CH3I 


OCONHCH 3 
]n(C2H5)2CH3C1 

OCONHCH 3 


OCONHCIR 

]n(C2H5)3I 
0C0N(CH3)2 


Mice 


0.15 


Mice 


Mice 


5.0 


Iv. 


Mice 


60 


LDh{ 


Mice 0.100 LDso 

(Seep. 219) (78 F) 


Mice 0.102 LD 50 

(See p. 219) (82 F) 


0.48 LDt 


LD, 


Sc.W. 

Mice 

0 . 122 * 

LDso 

Sc.W. 

Mice 

0.129 

LD 50 

Sc.W. pH4 

Mice 

0.135 

LD 50 

Sc.W. 

G. pig 
(See p. 219) 

0.097 

LD 50 

Sc. 

Mice 

0.29 

LDso 

Iv. 

Mice 

0.1 

LDgo 

Sc. 

Mice 

0.13 

LDso 

Sc.W. 

Mice 

O.OOOf 

LD^o 

Sc.W. 

Mice 

0.097 

LD50 

Sc.W. 

Mice 

0.1051 

LD50 

Sc.W. 

Mice 

(See p. 220 ) 

0.095 § 

LDso 

Sc.W. pm 

Mice 

0.100 

LDso 

Sc.W. 

Mice 

0.114 

LDso 

Sc.W. 

Mice 

0.107 

LDso 

Sc.W. 

Mice 

(See p. 220) 

0.102 

LDso 

Sc.W. 

Mice 

0.23 

LDso 


LD^o 


JN(CH 3 ) 2 (— CH0HC00H)2 


* At 80 F. 


t At 75 F. 


X At 77 F. 


§ At 76 F. 


SECRET 


218 


AROMATIC CARBAMATES 


Table 2, Section VII (Continued) 


Code 


Name 


Route 


Structure 


and 

solvent 

Species 

Dose 

mg/kg 

Effect 

Sc.W. 

Mice 

0.475 

LD^o 

Sc. 

Mice 

0.55 

LD^o 

Iv. 

Mice 

0.5 

LDso 

Sc. 

Mice 

0.45 

LD 50 


(See p. 220) 


Sc.W. 

Mice 

80 

2/2 



40 

2/2 



20 

0/2 



10 

0/2 

Sc.W. 

Mice 

0.125* 

LD 50 

Sc.W. 

Mice 

0.175t 

LD^o 

Iv.W. 

Mice 

0.089t 

LDso 


(See p. 220) 


Sc.W. 

Mice 

0.058t 

LD^o 

Sc.W. 

Mice 

0.108§ 

LDbo 

Sc.W. 

Mice 

O.IOOII 

LD^o 


(See p. 220) 


Sc.W. 

Mice 

10.0 

2/2 



5.0 

2/2 



2.5 

0/2 



1.0 

0/2 

Iv. 

Mice 

1.0 

LDso 


TL-1321 Carbamic acid, N,N-dimethyl- 
SB-24 3-dimethylaminophenyl 

ester methiodide 


AR-32 Carbamic acid, N,N-dimethyl- 
SB-23 3-dimethylaminophenyl 

TL-1394 ester methosulfate 

(Prostigmine) 

TL-1238 Carbamic acid, N,N-dimethyl- 
Prep. 1 3-diethylaminophenyl ester 
methiodide 

Prep. 2 
Prep. 3 
Prep. 3 

TL-1422 Carbamic acid, N,N-dimethyl- 
3-diethylaminophenyl ester 
methochloride 


TL-1481 Carbamic acid, N-ethyl-3-di- 
ethylaminophenyl ester 
methiodide 


AR-21 Carbamic acid, N-ethyl-3-di- 
methylaminophenyl ester 
methosulfate 


AR-36 Carbamic acid, N-ethyl-N- 
methyl-3-dimethylamino- 
phenyl ester methosulfate 


AR-33 Carbamic acid, N,N-diethyl- 
3-dimethylaminophenyl 
ester methosulfate 


AR-19 Carbamic acid, N-allyl-3-di- 
methylaminophenyl ester 
hydrochloride 


AR-34 Carbamic acid, N,N-diallyl- 
3-dimethylaminophenyl 
ester methiodide 


0C0N(CH3)2 
]n(CH,)3I 

OCON(CHa )2 

0C0N(CH3)2 

0C0N(CH3)2 
]n(C2H5)2CH3C1 
OCONHC 2 H 5 

]n(C2H5)2CH3I 
OCONHC 2 H 5 



Iv. 

OCONC 2 H 5 
]n(CH3)3S04CH3 

0C0N(C2H5)2 Iv. 

0C0NHCH2CH=CH2 Iv. 

JN(CH3)2-HC1 

0C0N(CH2CH=CH2)2 Iv. 

|n(CH3)3I 


Mice 


3.5 


Mice 


Mice 


150 


Mice 


LD. 


LD, 


LD, 


10 LDs 


* At 83 F. 


t At 75 F. 


% At 80 F. 


§ At 71 F. 


II At 73 F. 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


219 


Table 2, Section VII {Continued) 


Code 


Name 


Structure 


Route 

and 

solvent 


Dose 

Species mg/kg Effect 


AR-20 Carbamic acid, N-allyl-3-di- 
methylaminophenyl ester 
methosulfate 


AR-24 Carbamic acid, N-plienyl-3- 
dimethylaminophenyl 
ester hydrochloride 


AR-25 Carbamic acid, N-phenyl-3- 
dimethylaminophenyl ester 
methosulfate 


AR-22 Carbamic acid, N-benzyl-3- 
dimethylaminophenyl ester 
hydrochloride 


AR-23 Carbamic acid, N-benzyl-3- 
dimethylaminophenyl ester 
methosulfate 


T-1125 Carbamic acid, N-benzyl-3- 
dimethylaminophenyl ester 
methiodide 


TL-1308 Carbamic acid, N,N-penta- 
methylene-3-dimethyl- 
aminophenyl ester 
methiodide 

AR-35 Carbamic acid, N,N-penta- 
methylene-3-dimethyl- 
aminophenyl ester 
methosulfate 


TL-1346 Carbamic acid, N,N-penta- 
methylene-3-diethyl- 
aminophenyl ester 
methiodide 


T-1207 Carbamic acid, N-(4-methoxy- 
phenyl )-3-dimethylamino- 
phenyl ester methiodide 


TL-1442 Carbamic acid, N-(4-methoxy- 
phenyl )-3-diethylamino- 
phenyl ester methiodide 


0C0NHCH2CH=CH2 Iv. 


jN(CIl3)3S04CH3 

OCONHCeHs 

)n(CH3)2-HC1 
OCONHCgHs 

jN(CH3)3S04CH3 
OCONHCH 2 C 6 H 5 

OCONHCH2C6H5 
]n(CH3)3S04CH3 

OCONHCH.CeHs 

]n(CH3)3I 
OCONC 5 H 10 

]n(CH3)3T 

OCONC 5 H 10 


Iv. 


Iv. 


Iv. 


Iv. 


Sc. 

Sc. 


Sc.W. 


Iv. 


JN(CH3)3S04CH5 

OCONC 5 H 10 Sc.W. 

]n(C2H5)2 
CH 3 I 

OCONH<^^ ^0CH3 Sc. 

jN(CH3)3l 

OCONH<^^ ^OCHs Sc.P. 
jN(C2H5)2CH3l 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 

Rabbit 


Mice 


Mice 


Mice 


Mice 


Mice 


0.75 LDs. 


25 


50 


10 

5 

2.5 


5 

1 

0.2 

0.1 


0.24 


80 

40 

20 


LDfn 


LD, 


LD, 


0.1 LD, 


0.35 LDfio 

0.20 LD,o 


2/2 

2/2 

0/2 


LDs 


5/5 

3/5 

0/5 

0/5 


LD, 


0/2 

0/2 

0/2 


SECRET 


220 


AROMATIC CARBAMATES 


Table 2, Section VII {Continued) 


Code 

Route and 
solvent 

Species 

Effects 

(at various doses) 

TL-1I78 

Sc.W. 


0.10 

0.125 

0.25 

0.5 

1.0 



Rat 

... 

... 

0/2 

1/2 

2/2 



Rabbit 

0/2 

. . . 

2/2 

2/2 

2/2 



G. pig 

. . . 

0/2 

2/2 

2/2 

2/2 



Dog 

0/1 

0/1 

0/1 

0/2 

1/2 



Cat 

0/2 


0/2 

2/2 


TL-1434 

Sc.W. 


0.025 

0.050 

0.100 

0.200 




Rat 



0/2 

2/2 




Rabbit 

.... 

0/2 

1/2 

2/2 

. . . 



G. pig 

. . . 

0/2 

1/2 

2/2 

. . . 



Cat 

0/2 

2/2 

2/2 

. . . 




Dog 

0/2 

1/2 

1/2 

2/2 


TL-1435 

Sc.W. 


0.050 

0.100 

0.200 





Rat 


0/2 

2/2 





Rabbit 


0/2 

2/2 

. . . 

. . - 



G. pig 

. 0/2 

2/2 

2/2 


. . . 



Dog 


0/2 

2/2 



TL-1217 

Sc.W. 


0.05 

0.1 

0.2 

0.3 

0.4 



Rat 

... 

0/2 

0/2 

0/7 

6/7 



Rabbit 


0/2 

2/2 


• • . 



G. pig 

. . . 

0/2 

2/2 

. . . 

• • . 



Dog 

1/2 

2/2 

2/2 

. . . 

. . . 



Cat 

0/2 

2/2 

2/2 


• . . 



Sheep 

, . . 

0/2 

3/3 


. . . 



Goat 

. . . 


0/2 

2/5 

2/3 



Monkey 


0/2 

2/3 




Code 

Route and 
solvent 

Species 

Effects 

(at various doses) 

TL-1299 

Im.Imp. 


0.025 

0.05 

0.1 

0.2 

0.3 



(2nd sample) 


Goat 



0/1 

0/1 


1/1 





Monkey 

0/2 

0/4 

1/1 

1/1 


. . . 

. . . 

. . . 


Sc.W. 

Dog 


0/3 

1/3 

8/10 





TI^1317 

Sc.W. 


0.05 

0.1 

0.2 

0.3 






Rat 

... 

0/2 

3/5 

2/2 


... 

... 

... 



G. pig 

0/2 

1/5 

5/5 



. . . 

. . . 

. . . 



Rabbit 

0/2 

1/2 

2/2 

. . . 



. . . 

. . . 



Cat 


0/2 

2/2 






TL-1394 

Sc.W. 


0.2 

0.5 

1.0 

1.5 






Rat 


0/2 

1/2 

2/2 







Rabbit 

. . . 

0/2 

2/2 

2/2 



. . * 




G. pig 

0/2 

2/2 

2/2 

2/2 



. . . 




Dog 

0/2 

1/2 

1/2 

. . . 



. . . 




Cat 

0/2 

1/2 

2/2 






TL-1238 

Sc.W. 


0.05 

0.1 

0.15 

0.2 

0.3 

0.4 

1.0 



Rat 


... 

0/2 

0/2 


0/2 

1/2 

2/2 



Rabbit 

. . . 

0/2 

1/2 

2/2 


• • • 

. • . 

. . . 



G. pig 

0/2 

3/6 


2/2 


. . • 

. . . 

. . . 



Cat 

. . . 

0/2 

. . . 

2/2 



. . . 

. . • 



Dog 




0/2 


1/2 

2/2 


TI^1422 

Sc.W. 


0.05 

0.10 








Rabbit 

0/2 

2/2 

... 

... 



... 

... 



Dog 

0/2 

2/2 








SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


221 


Code 


Table 2' {Continued) 

VIII. Benzene compounds with one carbamate group and one quaternary ammonium group in the 

meta position and other substituents. 


Route 

and 


Dose 


Name 


Structure 

solvent 

Species 

mg/kg 

Effect 

OCONH 2 

Sc. 

Mice 

10 

2/2 

'X 



5 

2/2 

1 



1 

0/2 

lx(CH3)3l 



0.5 

0/2 

OCONHCH 3 

Sc.P. 

Mice 

80 

1/2 

\ 



40 

0/2 

1 



20 

0/2 

JN(CH3)2 

Sc.W. pH3 

lyiice 

80 

5/5 

/ 



40 

5/5 




20 

1/5 

OCONHCH 3 

Sc. 

Mice 

0 . 1 - 0.12 

LD^o 

\ 

Sc.W. 

Mice 

0.115 

LDso 

] 

Sc.W. pH4 

Mice 

0.108 

LDio 

In(CH3)3I 

Sc.W. pH4 

Mice 

0.107 

LDso 

s/ 

Sc.W. pH4 

Mice 

0.102 

LDso 

OCONHCH 3 





\ 

Sc.W. 

Mice 

0.075 

LDso 

1 

Sc.W. 

Mice 

0.064 

LDso 

Jn(CH3)3C1 

Ip.W. 

Mice 

0.088 

LDso 

y 

Sc.W. 

Rats 

0.100 

LDso 


Ip.W. 

Rats 

0.078 

LDso 


Oral W. 

Rats 

2.5 

LDso 


Sc.W. 

Dogs 

2.0 

4/10 




1.0 

0/3 


Im.Imp. 

Monkeys 

0.050 

1/4 


Sc.W. 

Mice 

0.070 

LDso 


Iv.W. 

Mice 

0.035 

LDso 

OCONHCH 3 

Sc.W. 

Mice 

0.110 

LDso 


TL-1256 Carbamic acid, 2-methyl-5- 
dimethylaminophenyl ester 
methiodide 


TL-1184 


T-1708 

TL-1071 


TL-1236 
Prep. 1 
Prep. 2 
Prep. 2 
Prep. 2 
Prep. 2 
Prep. 2 
Prep. 2 

Prep. 2 
Prep. 3 
Prep. 3 

TL-1185 


TL-1186 


TI^1340 


TL-1339 


TI^1257 

T-1739 


Carbamic acid, N-methyl-2- 
methyl-5-dimethylamino- 
phenyl ester 


Carbamic acid, N-methyl-2- 
methyl-5-dimethylamino- 
phenyl ester methiodide 


Carbamic acid, N-methyl-2- 
methyl-5-dimethylamino- 
phenyl ester methochloride 


Carbamic acid, N-methyl-2- 
methyl-5-dimethylamino- 
phenyl ester methosulfate 


Carbamic acid, N-methyl-2- 
methyl-5-dimethylamino- 
phenyl ester methosulfuric 
acid 

Carbamic acid, N-methyl-2- 
methyl-5-dimethylamino- 
phenyl ester ethiodide 


Carbamic acid, N-methyl-2- 
methyl-5-dimethylamino- 
phenyl ester ethochloride 


Carbamic acid, N-methyl-2- 
methyl-5-diethylamino- 
phenyl ester methiodide 


cm 


CH 3 


CHsf 


CHs 


CH 


CH 


CH 



CH 


N(CH3)3S04CH3 



cml 


OCONHCH3 

N(CH3)3HS04 
OCONHCH 3 

|n(CH3)2 

C 2 H 5 I 
OCONHCH 3 

N(CH3)2 

C 2 H 5 CI 
OCONHCH 3 

jN(C2H5)2CH3l 



Sc.W. 


Sc.W. 


(See p. 224) 


Mice 0.103 

(See p. 224) 


Mice 


0.090 


Sc.W. 


Mice 


Sc.W. 

? 


Mice 0.125 

Mice 0.2 


LDs 


IDs 


0.075* LD 


60 


LDio 

LD50 


♦ At 80 F. 


SECRET 


222 


AROMATIC CARBAMATES 




Table 2, Section VIII {Continued) 




Code 

Xame 

Route 

, and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


TL-1262 


TL-1261 


TL-1511 


TL-1512 


TL-1513 


T-1722 


T-1709 

TL-1501 


Carbamic acid, X-methyl-2- 
methy l-5-( N -benzyl-N - 
me t hylamino )pheny 1 
ester methochloride 


Carbamic acid, N-methyl-2- 
methyl-5-( N -ally 1-X -meth- 
ylamino)phenyl ester meth- 
ochloride 

Carbamic acid, X-imethyl-2- 
methyl-5-dimethylamino- 
phenyl ester /S-hydroxy- 
ethiodide 


Carbamic acid, X-methyl-2- 
methyl-5-dimethylamino- 
phenyl ester acetonylchlo- 
ride 


Carbamic acid, X-methyl-2- 
methyl-5-dimethylamino- 
phenyl ester carbethoxy- 
methochloride 


Carbamic acid, X-methyl-3- 
dimethylamino- 6 -ethyl- 
phenyl ester methiodide 


Carbamic acid, X-methyl-5- 
dimet hylamino- 2 -isopropyl- 
phenyl ester methiodide 


CH 



CH 



X(CH3)2l 

CH 2 CH 2 OH 
OCOXHCH 3 

CH3[ 1 

I Ix(CH3)2C1 

^ CH 2 COCH 3 
OCOXHCH 3 



C 2 H/ 


(CH3)2Chi 


X(CH3)2C1 

I 

CH 2 COOC 2 H 5 
OCOXHCH 3 


jX(CH3)3l 

OCOXHCH 3 


T-1778 Carbamic acid, X-methyl-2- 
cyclohexyl-5-dimethylamino- 
phenyl ester methiodide 



CeHnf 


T-1842 Carbamic acid, X-methyl-2- 
chloro-5-dimethylamino- 
phenyl ester hydrochloride 


T-1800 Carbamic acid, X-methyl-2- 
chloro-5-dimethylamino- 
phenyl ester methiodide 


TL-1523 Carbamic acid, X-methyl-3- 
isopropyl-5-dimethylamino- 
phenyl ester methiodide 



JX(CH3)3l 
OCOXHCH 3 

X(CH3)2*HC1 
OCOXHCH 3 

X(CH3)3l 

OCOXHCH 3 

(CH3)2HCI JX(CH3)3l 



Sc.W. 


Mice 


CH2C6H5CI 
OCOXHCH 3 

0 (CH3)2C1 

X— CH 2 CH=CH 2 
OCOXHCH 3 


Sc.W. 


Sc.W. 


Mice 


Mice 


Sc.W. 


Mice 


Sc.W. 


Mice 


Sc.W. 


Mice 


Mice 


10 

5 

2.5 

2 


2/2 

2/2 

0/2 

0/2 


0.077 LD, 


0.118* LD 50 


0.056t LD 50 


0.165t LD, 


(In saline) 

Mice 

0.75 

LD 50 

(In buffer 

Mice 

1.36 

LDto 

solution) 




? 

Mice 

250-300 

LDso 

(In buffer 




solution) 

Mice 

125 

LD^o 

Sc.W. 

Mice 

80 

0/2 



40 

0/2 



20 

0/2 

? 

Mice 

175 

LD^o 

? 

Mice 

45 

LDio 


LD, 


0.120 LDso 
(78 F) 


* At 76 F. 


t At 73 F. 


t At 74 F. 


SECRET 



CHEMICAL 

STRUCTURE AND TOXICITY 



223 


Table 

2, Section VIII {Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 

T-1768 

Carbamic acid, N-methyl-3- 
dimet hylamino-4-methyl- 
phenyl ester hydrochloride 

OCONHCH 3 ? 

(^X(CH 3 ) 2 -HC 1 

CH 3 

Mice 

10-15 

LD^o 


TL-1187 


Carbamic acid, N-methyl-4- 
methyl-3-dimethylamino- 
phenyl ester 


TL-1216 


TL-1453 


TL-1429 


TI^1188 


TI.-1354 


Carbamic acid, N-methyl-4- 
methyl-3-dimethylamino- 
phenyl ester methiodide 


Carbamic acid, N-methyl-4- 
methyl-3-dimethylamino- 
phenyl ester methochloride 


Carbamic acid, N-methyl-4- 
methyl-3-dimethylamino- 
phenyl ester ethiodide 


Carbamic acid, N-methyl-4- 
methyl-3-dimethylamino- 
phenyl ester methosulfate 


Carbamic acid, N-methyl-4- 
methyl-3-dimethylamino- 
phenyl ester allyl bromide 


OCONHCH3 



OCONHCH3 

]n(CH 3 ) 3 I 
'CH3 

OCONHCH3 

JN(CH3)3C1 
CH3 

OCONHCH3 

)x(CH3)2C2H5l 
'CH3 

OCONHCH3 

)n(CH3)3S04CH3 
CH3 

OCONHCH3 


Sc.P. 


Mice 


Sc.W. pH3 Mice 


Sc.W. Mice 


Sc.W. 


Mice 


Sc.W. 


Mice 


Sc.W. 


80 

40 

20 

10 

5 

80 

40 

20 

10 

5 

0.170 


Mice 

(See p. 224) 


Sc.W. 


Mice 


jN(CH3)2CH2CH=CH2Br 
CH3 


2/2 

2/2 

2/2 

0/2 

0/2 

5/5 

5/5 

5/5 

0/5 

0/5 

LDso 


0.130 
(75 F) 


0.155 
(72 F) 


LD, 


LD, 


0.200 LD 


50 


0.095 LDso 


TL-1338 Carbamic acid, N-methyl-4- 
methyl-3-methylbenzyl- 
aminophenyl ester metho- 
bromide 


T-1769 Carbamic acid, N-methyl-3- 
dimethylamino-4-isopro- 
pylphenyl ester hydrochlo- 
ride 


OCONnCH3 

(^N^H2C6H5 

CH3 (CH3)2Br 
OCONHCH3 

(^N(CH3)2-HC1 

CH(CH 3)2 


Sc.W. Mice 


(In buffer Mice 
solution) 


10 3/3 

5 ■ 2/3 

1 0/3 

0.5 0/3 


70 LDso 


SECRET 


224 


AROMATIC CARBAMATES 




Table 2, Section VIII (Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 




TL-1502 Carbamic acid, N-methyl-3- 
dimethylamino-4-isopro- 
T-1721 pylphenyl ester methiodide 


T-1770 Carbamic acid, N-methyl-2,4- 
dimethyl-5-dimethylamino- 
phenyl ester hydrochloride C H 3 


T-1767 Carbamic acid, N-methyl-2,4- 
dimethyl-5-dimethylamino- 
phenyl ester methiodide 


T-1740 Carbamic acid, N-methyl-3- 
dimethylamino-5-methyl- 
phenyl ester methiodide 


T-1741 Carbamic acid, N-methyl-3- 
dimethylamino-4-ethyl- 
phenyl ester methiodide 


TL-1237 Carbamic acid, N,N-dimethyl- 
2-methyl-5-dimethylamino- 
phenyl ester methiodide CHsf 


TL-1423 Carbamic acid, N, N-dimethyl- 
2-methyl-5-diethylamino- 
phenyl ester methiodide CH 3 


TL-1325 Carbamic acid, N,N-dimethyl- 
4-methyl-3-dimethylamino- 
phenyl ester methiodide 


TL-1487 Carbamic acid, N-methyl-N- 
methoxy-2-met hy 1-5-dimeth- 
ylaminophenyl ester meth- CH 3 I 

iodide 

TL-1300 Carbamic acid, N,N-penta- 

methylene-2-methyl-5-dimeth- 
ylaminophenyl ester meth- CH 3 

iodide 

TL-1355 Carbamic acid, N,N-penta- 
methylene-4-methyl-3-di- 
methylaminophenyl ester 
methiodide 


OCONHCH 3 

)n(CH3)3I 

CH(CH3)2 

OCONHCH 3 

)n(CH3)2-HC1 
CHs 

OCONHCH 3 

X(CH3)3l 
CH 3 

OCONHCH 3 

N(CH3)3l 
OCONHCH 3 

)n(CH3)3I 
C 2 H 5 

0C0N(CH3)2 

]n(CH3)3I 
0C0N(CH3)2 

)n(C2H5)2CH3I 
0C0N(CH3)2 

]n(CH3)3I 
CH 3 

OCONCH 30 CH 3 
]n(CH3)3I 

OCONC 3 H 10 

jN(CH3)3l 

OCONC 5 H 10 


Sc.W 



Sc.W. 


Sc.W. 


Sc.W. 


Sc.W. 


Sc.W. 


Sc.W. 


Mice 

Mice 

Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


0.51 
(75 F) 
1 


10 


0.1 


0.17 


0.4 


10 

5 

2.5 

2.0 

1.0 

10 

5 

0.5 

0.25 

10 

5 

1 

0.5 

0.2 

2.5 

1.0 

0.5 

0.25 

80 

40 

20 


20 

10 

5 

1 


LD, 


LD, 


LD 


50 


LD, 


LD, 


2/2 

2/2 

2/2 

0/5 

0/5 

2/2 

2/4 

0/5 

0/5 

2/2 

2/2 

1/2 

0/2 

0/2 

5/7 

0/7 

1/10 

0/10 

1/2 

0/2 

0/2 


2/2 

2/2 

0/2 

0/2 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


225 


Code 


Name 


Table 2, Section VIII {Continued) 


Route 

and 

Structure solvent 


Dose 

Species mg/kg Effect 


TL-1239 Carbamthiolic acid, N-methyl- 
3-dimethylamino-4-meth- 
ylphenyl ester methiodide 


SCONHCH 3 Sc.W. 

(^N(CH3)3l 


Mice 

80 

0/2 


40 

0/2 


20 

0/2 


CH3 


Code 

Route and 
solvent 

Species 


(at 

p]ffects 

various doses) 

TL-1185 

Sc.W. 


0.1 

0.2 

0.3 

0.4 

1.0 



Rat 

0/2 

1/2 

2/2 





Rabbit 

0/2 

1/2 

1/2 

2/2 

. . . 



G. pig 

0/2 

2/2 

. . . 

. . . 

. . . 


' 

Dog 

0/2 

1/2 

1/2 

. . . 

. . . 



Cat 

0/2 

2/2 

2/2 

• . . 

- . . 



Sheep 

0/1 

0/2 

0/2 

0/2 

1/1 



Goat 

. . . 

0/2 

2/5 

0/2 

0/2 



Monkey 


0/2 




TL-1186 

Sc.W. 


0.05 

0.1 

0.2 

0.3 




Rat 


0/2 

2/2 





Rabbit 

. . - 

0/2 

2/2 

. . . 

. . . 



G. pig 

0/2 

2/2 

2/2 

. . . 

. . . 



Dog 


0/2 

1/2 

0/2 


TL-1188 

Sc.W. 


0.1 

0.2 

0.3 

0.4 




Rat 

0/2 

1/2 

0/2 

0/2 

... 



Rabbit 

0/2 

1/2 

1/2 

. • . 

• • • 



G. pig 

0/2 

2/2 

. . . 

. . . 

. . . 



Dog 

0/2 

2/2 

1/2 

1 


IX. Benzene compounds with one carbamate group and one quaternary ammonium group in the 

para position (including thiocarbamates). < 


Code Name 


. TL-943 Carbamic acid, N-methyl-4- 
aminophenyl ester hydro- 
chloride 


T-1088 Carbamic acid, N-methyl-4- 
AR-17 dimethylaminophenyl ester 

TL-1097 methiodide 


TL-1469 Carbamic acid, N-methyl-4- 
dimethylaminophenyl ester 
ethiodide 


Route 

and Dose 

Structure solvent Species mg/kg Effect 


OCONHCH 3 Sc.W. 



NH2-HC1 


OCONHCH 3 Sc. 



N(CH3)3l 


OCONHCH 3 Sc.W. 



N(CH3)2C2H5l 


Mice 

80 

2/2 


40 

0/2 


20 

0/2 


Mice 

50 

LD 50 

Mice 

2 

LD^o 

Mice 

80 

2/2 


40 

2/2 


20 

2/2 


10 

0/2 


5 

0/2 

Mice 

40 

2/2 


20 

2/2 


10 

0/2 


5 

0/2 


SECRET 


226 


AROMATIC CARBAMATES 


Table 2, Section IX {Continued) 


Code 


Name 


Structure 


Route 

and 

solvent 


Species 


TL-1456 Carbamic acid, N-methyl-4- 
dimethylaminophenyl ester 
allyliodide 


TL-1431 Carbamic acid, N-methyl-4- 
diethylaminophenyl ester 
methiodide 


TL-1432 Carbamic acid, N-methyl-4- 
diethylaminophenyl ester 
allyliodide 


TL-1430 Carbamic acid, N-methyl-4- 
diethylaminophenyl ester 
ethiodide 


TL-1457 Carbamic acid, N,N-dimethyl- 
4-dimethylaminophenyl 
ester ethiodide 


TL-1486 Carbamic acid, N,N-dimethyl- 
4-dimethylaminophenyl ester 
/3-hydroxyethobromide 


TL-1470 Carbamic acid, N,N-dimethyl- 
4-dimet hylaminopheny 1 
ester allyliodide 


TL-1458 Carbamic acid, N,N-dimethyl- 
4-diethylaminophenyl ester 
methiodide 


TL-1472 Carbamic acid, N,N-dimethyl- 
4-diethylaminophenyl ester 
allyliodide 


OCONHCH3 Sc.W. Mice 


(CH3)2NCH2CH=CH2l 

OCONHCH3 Sc.W. Mice 


N(C2H5)2CH3l 

OCONHCH3 Sc.W. Mice 


N(C2H5)2l 

CH2CH=CH2 

OCONHCH3 Sc.W. Mice 


N(C2H5)3l 

0C0N(CH3)2 Sc.W. Mice 


N(CH3)2C2H6l 

0C0N(CH3)2 Sc.W. Mice 


N(CH3)2Br 

I 

CH 2 CH 2 OH 

0C0N(CH3)2 Sc.W. Mice 


N(CH3)2l 

CH2CH=CH2 

0C0N(CH3)2 Sc.W. Mice 


N(C2H5)2CH3l 

0C0N(CH3)2 Sc.W. Mice 


Dose 

mg/kg 


Effect 


10 

2/2 

5 

2/2 

2.5 

0/2 

40 

2/2 

20 

1/2 

10 

0/2 

5 

0/2 

40 

2/2 

20 

1/2 

10 

0/2 

5 

0/2 

80 

2/2 

40 

1/2 

20 

0/2 

10 

0/2 

80 

1/2 

40 

0/2 

20 

0/2 

80 

2/2 

40 

1/2 

20 

0/2 

10 

0/2 

80 

2/2 

40 

1/2 

20 

0/2 

10 

0/2 

80 

0/2 

40 

0/2 

20 

0/2 

80 

0/2 

40 

0/2 

20 

0/2 


N(C2H5)2l 

I 

CH2CH=CH2 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


227 


Table 2, Section IX (Continued) 


Code Name 


Route 

and Dose 

Structure solvent Species mg /kg Effect 


TL-1471 Carbamic acid, N,N-dimethyl- 
4-diethylaminophenyl ester 
ethiodide 


TL-1229 Carbamthiolic acid, N-methyl- 
4-nitrophenyl ester 


TLr-1258 Carbamthiolic acid, N-methyl- 
4-dimethylaminophenyl 
ester methiodide 


TL-1054 Carbamthiolthionic acid, N,N- 
dimethyl-4-nitrophenyl 
ester 


TL-1 128 Carbamthiolthionic acid, N,N- 
dimethyl-4-aminophenyl 
ester hydrochloride 


TL-1 1 79 Carbamthiolthionic acid, N, N- 
dimethyl-4-dimethylamino- 
phenyl ester methiodide 


0C0N(CH3)2 


Sc.W. Mice 


80 

40 

20 


N(C2H5)3l 

SCONHCHs 


NO2 

SCONHCH 3 


Sc.P. Mice 


Sc.W. Mice 


80 

40 

20 

10 


80 

40 

20 


N(CH3)3l 

SCSN(CH3)2 


Sc.P. Mice 


40 

20 


NO 2 

SCSN(CH3)2 


Sc.W. Mice 


NH 2 HCI 

SCSN(CH3)2 


Sc.W. Mice 

(suspension) 


80 

40 

20 


N(CH3)3l 


0/2 

0/2 

0/2 


1/2 

1/2 

0/2 

0/2 


0/2 

0/2 

0/2 


0/2 

0/2 


0/2 

0/2 

0/2 


1/2 

0/2 

0/2 


X. Benzene compounds with one carbamate group and one quaternary ammonium group in the 
para position and other substituents. 


TL-1478 Phenol, 3-isopropyl-4-dimeth- 
ylamino-, methiodide 


TLr-1322 Carbamic acid, N-methyl-2- 
isopropyl-4-dimethylamino- 
phenyl ester methiodide 


OH 


(^CH(CH3)2 

N(CH3)3l 

OCONHCH 3 


CH(CH3)2 


Sc.W. 


Sc.W. 


Mice 


Mice 


80 

40 

20 

10 


0.51 


TLr-1446 Carbamic acid, N-methyl-3- 
methyl-4-dimethylamino- 
phenyl ester methiodide 


N(CH3)3l 

OCONHCH 3 



N(CH3)3l 


Sc.W. Mice 


10 

5 

1 

0.5 

0.25 


2/2 

2/2 

0/2 

0/2 


LD50 


2/2 

2/2 

1/2 

1/2 

0/5 


SECRET 


228 


AROMATIC CARBAMATES 


Table 2, Section X {Continued) 


Code 


Route 


Name 


Structure 


and 


Dose 


solvent 

Species 

mg/kg 

Effec 

Sc.W. 

Mice 

10 

2/2 



5 

2/2 



1 

2/2 



0.5 

2/2 



0.25 

0/5 

Sc.W. 

Mice 

0.24 
(73 F) 

IjD^o 

Sc.W. 

Mice 

10 

2/2 



5 

2/2 



1 

1/2 



0.5 

0/2 



0.25 

0/2 

Sc.W. 

Mice 

0.145 
(74 F) 

LD 50 

Sc.W. 

Mice 

0.39 
(78 F) 

LD 50 

Sc.W. 

Mice 

10 

2/2 



5 

2/2 



2.5 

2/2 



1.0 

1/2 



0.5 

0/2 

Sc.W. 

Mice 

0.067 

LD 50 


Mice 

0.070 
(79 F) 

LDso 

pH 4 

Mice 

0.064 

LD 50 

Sc.W. 

Mice 

0.045* 

LD 50 

Sc.W. 

Mice 

0.047t 

LD^o 

Sc.W. pH 4 

Mice 

0.050t 

LDso 

Sc.W. 

Rats 

0.103§ 

LDio 


(See p. 234) 


Sc.W. 

Mice 

0.057t 



TL-1447 


TL-1448 


TL-1454 


TL-1467 


TL-1468 


TL-1381 


TL-1327 
Prep. 1 
Prep. 2 

Prep. 2 

TL-1345 
Prep. 1 
Prep. 2 
Prep. 2 
Prep. 2 

TL-1522 


Carbamic acid, N-methyl-3- 
methyl-4-dimethylamino- 
phenyl ester ethiodide 


Carbamic acid, N-methyl-3- 
methyl-4-dimethylamino- 
phenyl ester allyliodide 


Carbamic acid, N-methyl-3- 
methyl-4-diethylamino- 
phenyl ester methiodide 


Carbamic acid, N-methyl-3- 
ethyl-4-dimethylamino- 
phenyl ester methiodide 


Carbamic acid, N-methyl-3- 
propyl-4-dimethylamino- 
phenyl ester methiodide 


Carbamic acid, N-methyl-3- 
isopropyl-4-dimethylamino- 
phenyl ester hydrochloride 


Carbamic acid, N-methyl-3- 
isopropyl-4-dimethylamino- 
phenyl ester methiodide 


Carbamic acid, N-methyl-3- 
isopropyl-4-dimethylamino- 
phenyl ester methochloride 


Carbamic acid, N-methyl-3- 
isopropyl-4-dimethylamino- 
phenyl ester allyl bromide 


OCONHCH3 


JCH3 

'N(CH3)2C2H5l 

OCONHCH3 


CH3 


(CH3)2NCH2CH=CH2l 

OCONHCH3 


CH3 


TL-1475 Carbamic acid, N-methyl-3- 


N(C2H5)2CH3l 

OCONHCH3 


JC2H5 

N(CH3)3l 

OCONHCH3 


JCH2CH2CH3 

N(CH3)3l 

OCONHCH3 


jCH(CH3)2 

N(CH3)2-HC1 

OCONHCH3 


Jch(ch3)2 

N(CH 3 ) 3 l 

OCONHCH3 


Jch(ch3)2 

N(CH 3 ) 3 C 1 

OCONHCH3 


Jch(ch 3)2 

(CH3)2'NCH2CH=CH2Br 
OCONHCH3 


Sc.W. 


Mice 


10 


2/2 



SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


229 




Table 2, Section X {Continued) 




Code 

Xame 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


TL-1476 Carbamic acid, N-methyl-3- 
amyl-4-dimethylamino- 
phenyl ester methiodide 


TL-1416 Carbamic acid, N-methyl-3- 
cy cl opentyl-4-dimet hyl- 
aminophenyl ester meth- 
iodide 


TL-1490 Carbamic acid, N-methyl-3- 
hexyl-4-dimethylamino- 
phenyl ester methiodide 


TL-1489 Carbamic acid, N-methyl-2,o- 
dimethyl-4-dimethylamino- 
phenyl ester ethiodide 


TL-1254 Carbamic acid, X-methyl-3,5- 
dimethyl-4-dimethylamino- 
phenyl ester hydroiodide 


TLr-1482 Carbamic acid, N-methyl-4- 
dimethylaminocarvacryl 
ester ethiodide 



CH 2 — CHo 

X(CH3)3l 

OCOXHCH 3 


CeH, 


X(CH3)3l 

OCOXHCH 3 

CH3f 1 

X(CH3)2C2H5l 

OCOXHCH 3 



CH 3 


X(CH3)2HI 

OCOXHCH 3 

JcH(CH3)2 


SB-26 Carbamic acid, X-methyl-4- 
dimethylaminothymyl 
ester hydrochloride 


SB-27 Carbamic acid, X"-methyl-4- 
dimethylaminothymyl 
ester methiodide 


X(CH3)2C2H5l 

OCOXHCH 3 
(CH3)2Hcf 1 

I Jch3 

X(CH3)2-HC1 

OCOXHCH 3 


(CH3)2HCf 


TL-1451 Carbamic acid, X-methyl-2,6- 
diisopropyl-4-dimethyl- 
aminophenyl ester meth- 
iodide 


SB-2 Carbamic acid, X,X-dimethyl- 
4-dimethylamino-2-methyl- 
phenyl ester hydrochloride 


JCH 3 

'X(CH3)3l 

OCOXHCH 3 


(CH 



X(CH3)2-HC1 


Sc.W. 


Sc.W. 


Sc.W. 


Sc.W. 


Sc. 


Sc. 


Sc.W. 


Sc. 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


10 

5 

1 

0.5 


10 

5 

1 

0.5 


10 

5 

2.5 

1.0 

0.5 


80 

40 

20 

10 


23 


80 

40 

20 


>400 


2/2 

2/2 

0/2 

0/2 


2/2 

2/2 

0/2 

0/2 


2/2 

2/2 

2/2 

0/2 

0/5 


0.325* LD, 


2/2 

2/2 

0/2 

0/2 


0.145t LZ>5 




0.22 LZ)5o 


2/2 

0/2 

0/2 




* At 75 F. 


t At 73 F. 


SECRET 


230 


AROMATIC CARBAMATES 




Table 2, Section X {Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


SB-3 Carbamic acid, N,N-dimethyl- 
4-dimethylamino-2-methyl- 
phenyl ester methiodide 


0C0N(CH3)2 

Vhs 


Sc. 


Mice 


6.5 


LD, 


TL-1313 Carbamic acid, N,N-dimethyl- 
4-dimethylamino-2-isopropyl- 
phenyl ester methiodide 


SB-4 Carbamic acid, N,N-dimethyl- 
4-dimethylamino-3-methyl- 
phenyl ester hydrochloride 


SB-5 Carbamic acid, N,N-dimethyl- 
4-dimethylamino-3-methyl- 
phenyl ester methiodide 


TL-1449 Carbamic acid, N,N-dimethyl- 
3-methyl-4-dimethylamino- 
phenyl ester ethiodide 


TL-1455 Carbamic acid, N, N-dimethyl- 
3-methyl-4-diethylamino- 
phenyl ester methiodide 


SB-6 Carbamic acid, N,N-dimethyl- 
4-dimethylamino-3-ethyl- 
phenyl ester hydrochloride 


N(CH3)3l 

0C0N(CH3)2 

|^CH(CH3)2 

N(CH3)3l 

0C0N(CH3)2 

|^CH3 

N(CH3)2-HC1 

0C0N(CH3)2 

(^CH3 

N(CH3)3l 

0C0N(CH3)2 


^CH3 

N(CH3)2C2H5l 

0C0N(CH3)2 


^CH3 

N(C2H5)2CH3l 

0C0N(CH3)2 


^C2H3 

N(CH3)2-HC1 


Sc.W. 


Sc. 


Sc. 


Sc.W. 


Sc.W. 


Sc. 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


0.47 


105 


13.0 


80 

40 

20 

10 


45 


LZ), 


LD, 


LD, 


1/2 

0/2 

0/2 


1/2 

1/2 

0/2 

0/2 


LD, 


SB-7 

Carbamic acid, N,N-dimethyl- OCON(CH 3)2 

Sc. 

Mice 

1.15 

LD 50 

TL-1412 

4-dimethyl amino-3-ethyl- /\ 

Sc.W. 

Mice 

10 

2/2 


phenyl ester methiodide | ] 



5 

2/2 


1 )C2H5 



1 

1/2 


V 



0.5 

0/2 


N(CH3)a 





SB-8 

Carbamic acid, N,N-dimethyl- OCON(CH 3)2 

Sc. 

Mice 

0.075 

LD 50 

TI^599 

4-dimethylamino-5-isopro- 

Sc.W. 

Mice 

0.080 

LD 50 


pylphenyl ester methiodide | ] 

Sc.W. 

Mice 

0.089 

LDio 


1 IcH(CH3)2 

Ip.W. 

Mice 

0.168 

LDso 


V 

Ip.W. 

Mice 

0.220 

LD^q 


N(CH3)jI 

Ip.W. 

Mice 

0.265 

LDao 




(See p. 234) 



TL-1460 

Carbamic acid, N,N-dimethyl- OCON(CH 3)2 

Sc.W. 

Mice 

10 

2/2 


3-propyl-4-dimethylamino- /\ 



5 

2/2 


phenyl ester methiodide | ] 



1 

2/2 


1 JCH 2 CH 2 CH 3 



0.50 

0/2 


V 



0.25 

0/2 


N(CH3)3l 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


231 


Code 


Name 


Table 2, Section X {Continued) 


Route 

and 

Structure solvent 


Dose 

Species mg /kg Effect 


TL-1443 


TL-1521 


TL-1461 


TI^1462 


TL-1463 


TL-1464 


TL-1417 


TL-1466 


SB-28 


SB-29 


Carbamic acid, N,N-dimethyl- 
3-isopropyl-4-dimethyl- 
aminophenyl ester metho- 
chloride 


Carbamic acid, N,N-dimethyl- 
3-isopropyl-4-dimethyl- 
aminophenyl ester ethio- 
dide 


Carbamic acid, N,N-dimethyl- 
3-butyl-4-dimethylamino- 
phenyl ester methiodide 


Carbamic acid, N,N-dimethyl- 
3-amyl-4-dimethylamino- 
phenyl ester methiodide 


Carbamic acid, N,N-dimethyl- 
3-hexyl-4-dimethylamino- 
phenyl ester methiodide 


Carbamic acid,N,N-dimethyl- 
3-heptyl-4-dimethylamino- 
phenyl ester methiodide 


Carbamic acid, N,N-dimethyl- 
3-cyclopentyl-4-dimethyl- 
aminophenyl ester 
methiodide 


Carbamic acid, N,N-dimethyl- 
3-pheny 1-4-dime thy lami no- 
phenyl ester methiodide 


Carbamic acid, N-methyl-4- 
dimethylaminocarvacryl 
ester hydrochloride | 

(CH3)2HC1 


0C0N(CH3)2 


^CH(CH3)2 

N(CH3)3C1 

0C0N(CH3)2 


^CH(CH3)2 

N(CH3)2C2H5l 

0C0N(CH3)2 


^(CH2)3CH3 

N(CH3)3l 

0C0N(CH3)2 


^(CH2)4CH3 

N(CH3)3l 

0C0N(CH3)2 


^(CH2)oCH3 

N(CH3)3l 

0C0N(CH3)2 


^(CH2)6CH3 

N(CH3)3l 

0C0N(CH3)2 

) CH 2 — CH 2 

< 

CH 2 — CH 2 
N(CH3)3l 
0C0N(CH3)2 


^CeH3 

N(CH3)3l 

OCONHCH 3 

Vh3 


Carbamic acid, N-methyl-4- 
dimethylaminocarvacryl 
ester methiodide 


N(CH3)2*HC1 

OCONHCH 3 


(CH3)2HC 


CH. 


Sc.W. 


Sc.W. 


Sc.W. 


Sc.W. 


Sc.W. 


Sc.W. 


Sc.W. 


Sc.W. 


Sc. 


Sc. 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


0.065 LD^q 
(73 F) 


0.182 LD 50 
(71 F) 


10 

2/2 

5 

2/2 

1 

0/2 

0.5 

0/2 

10 

2/2 

5 

2/2 

1 

0/2 

0.5 

0/2 

10 

2/2 

5 

2/2 

1 

0/2 

0.5 

0/2 


80 

2/2 

40 

2/2 

20 

0/2 

10 

0/2 


10 

2/2 

5 

2/2 

1 

2/2 

0.5 

0/2 


80 

0/2 

40 

0/2 

20 

0/2 

2.1 

LDsa 


0.09 LD^o 


N(CH3)3l 


SECRET 


232 


AROMATIC CARBAMATES 




Table 2, Section X (Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


SB-1 1 Carbamic acid, N,N-dimethyl- 
4-dimethylaminocarvacryl 
ester hydrochloride 


(CH3)2HCI 


SB-12 Carbamic acid, N,N-dimethyl- 
4-dimethylaminocarvacryl 
ester methiodide 


0C0N(CH3)2 

■N(CH3)2-HC1 

0C0N(CH3)2 


(CH3)2HCI 


SB-9 Carbamic acid, N,N-dimethyl- 
4-dimethylaminothymyl 
ester hydrochloride 


(CH3)2HC/ 


SB-10 Carbamic acid, N,N-dimethyl- 

4-dimethylaminothymyl , 

ester methiodide (CH 3 ) 2 HC| 


TL- 1 1 95 Carbamic acid, N , N -dimethy 1- 

3,5-dimethyl-4-nitrophenyl 
ester 


N(CH3)3l 

0C0N(CH3)2 

Jc„. 

N(CH3)2-HC1 

0C0N(CH3)2 

JoH . 

N(CH3)3l 

0C0N(CH3)2 


CH 3 JCH 3 


N 02 

0C0N(CH3)2 


TL-1253 Carbamic acid, N,N-dimethyl- 
3,5-dimethyl-4-dimethyl- 
aminophenyl ester hydro- f ] 

iodide CH 3 JCHs 


TL-1377 Carbamic acid, N-ethyl-3,5- 
diisopropyl-4-dimethyl- 
aminophenyl ester 


N(CH3)2HI 
OCONHC 2 H 5 

(CH3)2ChI JcH(CH3)2 


TLf-1077 Carbamic acid, N,N-diethyl- 
3,5-dimethyl-4-nitroso- 
phenyl ester 


TL-1197 Carbamic acid, N,N-diethyl- 
3,5-dimethyl-4-nitrophenyl 
ester 


TL-967 Carbamic acid, N,N-diethyl- 
4-dimethylaminothymyl 
ester methiodide 


N(CH3)2 

0C0N(C2H5)2 


CH 3 CH 3 


NO 

0C0N(C2H6)2 


CH 3 I ICH 3 


(CH3)2HCr 


NO 2 

PC0N(C2H5)2 

JoH. 

N(CH3)3l 


Sc. 


Sc. 


Sc. 


Sc. 


Sc.P. 


Sc.W. 


Sc.W. 


Sc.O. 


Sc.P. 


Sc.W. 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


Mice 


20 


160 


80 

40 

20 


80 

40 

20 


80 

40 

20 


80 

40 

20 


80 

40 

20 


80 

40 

20 

10 




0.24 LD,c 


LD,, 


0.72 LDsc 


0/2 

0/2 

0/2 


0/2 

0/2 

0/2 


0/2 

0/2 

0/2 


0/2 

0/2 

0/2 


0/2 

0/2 

0/2 


2/2 

1/2 

0/2 

0/2 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


233 




Table 2, Section X (Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


TL-778 Carbamic acid, N,N-diethyl- 
eneoxy-4-dimethylamino- 
carvacryl ester metho- 
chloride 


TL-776 Carbamic acid, N,N-diethyl- 
eneoxy-4-dimet hylamino- 
carvacrvl ester methiodide 


TL-1073 Carbamic acid, N,N-6is(2- 
chl oroethyl )-4-dimethyl- 
aminothymyl ester metho- 
chloride 


TL-1079 Carbamic acid, N-(2-chloro- 
ethyl )-N-ethyl-4-nitroso- 
thymyl ester 


(CH3)2HCI 


(CH3)2HCt 

iCR,hCR( 


0C0NC4H,0 
jCHs 

N(CH3)3C1 

OCONC 4 H 3 O 

jCHa 

N(CH3)3l 

0C0N(CH2CH2C1)2 

]cH3 

N(CH3)3C1 

C 2 H 5 


Sc.W. 


Mice 


Sc.W. 


Mice 


Sc.W. 


Mice 


Sc.O. 


Mice 


OCON 


(CH3)2CHf 


\ 


CH 2 CH 2 CI 


CH 3 


NO 


TL-1074 


methiodide 


Carbamic acid, N-(2-chloro- 
ethyl )-N -ethyl-4-dimeth- 
ylaminothymyl ester 
methochloride 


(CH3)2HCf 


CH 3 


CH 2 CH 2 CI 


N(CH3).3l 


C 2 H 5 


Sc.W. 


Mice 


OCON 


(CH3)2CHf 


CH 2 CH 2 CI 


JCH 3 
N(CH3)3C1 


ester 



80 

40 

20 


80 

40 

10 


80 

40 

20 

10 


80 

40 

20 


80 

40 

20 

10 


0/2 

0/2 

0/2 


1/2 

0/2 

0/2 


1/2 

1/2 

0/2 

0/2 


0/2 

0/2 

0/2 


TL-1080 Carbamic acid, N,N-&is(2- 

OCONCCHjCHiClH 

Sc.O. 

Mice 

80 

0/2 

chloroethyl )-4-ni t ro- 

A 



40 

0/2 

thymyl ester 

(CHa),CHf 1 



20 

0/2 


Mch, 






V 

NO 2 





TL-969 Carbamic acid, N-(2-chloro- 

C 2 H 5 

Sc.W. 

Mice 

80 

2/2 

ethyl )-N-ethyl-4-dimeth- 

/ 



40 

0/2 

ylaminothymyl ester 

OCON 



20 

0/2 


2/2 

2/2 

0/2 

0/2 


TL-1048 Carbamic acid, N,N-6/.s(2- 

0C0N(C2H4C1)2 

Sc.W. 

' Mice 

80 

0/2 

chloroe thy 1 )-4-di me thy 1- 

/\ 



40 

0/2 

aminothymyl ester meth- 

(CH3)2HCf 1 



20 

0/2 

iodide 

1 ICH 3 






N(CH3)3l 





TL-1 198 Carbamic acid, N-(2-chloro- 

C 2 H 5 

Sc.P. 

Mice 

80 

0/2 

ethyl)-N-ethyl-3,5-di- 

/ 



40 

0/2 

methyl-4-nitrophenyl 

OCON— CH 2 CH 2 CI 



20 

0/2 


SECRET 


234 


AROMATIC CARBAMATES 


Table 2, Section X {Continued) 


Code 


Name 


Route 

and Dose 

Structure solvent Species mg/kg Effect 


TL-1075 Carbamic acid, N,N-6zs(2- 

chloroethyl)-3,5-dimethyl- 
4-nitrosophenyl ester 


0C0N(CH2CH2C1)2 Sc.O. 



Mice 


80 

1/2 

40 

0/2 

20 

0/2 


NO 


TL-1255 Carbamic acid, N,N-6is{2- 

chloroethyl )-3 , 5-dimethy 1-4- 
nitrophenyl ester trihy- 
drate 


TL-1413 Carbamic acid, N,N-penta- 
methylene-3-ethyl-4-di- 
methylaminophenyl ester 
meth iodide 


TL-1414 Carbamic acid, N,N-penta- 
methylene-3-isopropyl-4- 
dimethylaminophenyl ester 
methiodide 


TL-1418 Carbamic acid, N,N-penta- 
methylene-3-cyclopentyl- 
4-dimethylaminophenyl 
ester methiodide 


CH 


TL-1049 Carbamic acid, N,N-penta- 
methylene-4-dimethyl- 
aminothymyl ester metho- (CH3)2CHf 

chloride . I 


TL-968 Carbamic acid, N,N-penta- 
methylene 4-dimethyl- 
aminothymyl ester meth- (CH 3 ) 2 HC 
iodide ! 


0C0N(CH2CH2C1)2-3H20 Sc.P. 


Sc.W. 


Mice 



^C2H5 

N(CH3)3l 

OCONC5H10 

Ich(ch3)2 

N(CH3)3l 

OCONC5H10 
A. CH2— CHs 

J^< 

CH2— CH2 
N(CH3)3l 

OCONC5H10 

)CH3 

N(CH 3 ) 3 C 1 

OCONC5H10 



Sc.W. 


Sc.W. 


Mice 


Mice 


Mice 


Sc.P. 


Sc.W. 


Mice 


Mice 


80 

0/2 

40 

0/2 

20 

0/2 


80 

2/2 

40 

2/2 

20 

2/2 

10 

0/2 

5 

0/2 


0.51 LD50 
(78 F) 


80 2/2 

40 2/2 

20 1/2 

10 0/2 


0.36 LDsto 


0.44 ZvDso 


TL-777 

Carbamic acid, N,N-penta- 

OCONC3H10 

Sc.W. 

Mice 

3 

2/3 


methylene-4-dimethyl- 

A 



2 

0/3 


aminocarvacryl ester 

( ICH 3 



1 

0/3 


methiodide 

(ch3)2HcI J 

Iv.W. 

Mice 

3 

3/5 



V 



2 

0/5 



N(CH3)3l 





TL-1196 

Carbamic acid, N,N-penta- 

OCONCsHio 

Sc.P. 

Mice 

80 

1/2 


methylene-3,5-dimethyl- 

A 



40 

1/2 


4-nitrophenyl ester 

f 1 



20 

0/2 



CH3I jCH3 



10 

0/2 


NO2 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


235 




Table 2, Section X {Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


TL-1260 Carbamic acid, N,N-penta- 
methylene-3,5-dimethyl- 
4-dimethylaminophenyl 
ester hydroiodide 


TL-1465 Carbamic acid, N-phenyl- 
3-isopropyl-4-dimethyl- 
aminophenyl ester meth- 
iodide 


OCONCsHio 

cn.(^cn3 

N(CH3)2 hi 
OCONHC ells 

(^CH(CH3)2 

N(CH3)3l 


Sc.W. 

Mice 

80 

0/2 



40 

0/2 



20 

0/2 


Sc.W. 

Mice 

40 

2/2 



20 

2/2 



10 

2/2 



5 

1/2 



2.5 

0/2 



Route and 




Plffects 



Code 

solvent 

Species 


(at various doses) 


TL-1448 

Sc.W. 


0.2 

0.3 

0.5 

1.0 




Rat 


0/2 

2/2 





Rabbit 

. . . 

0/2 

2/2 


• . . 



G. pig 

0/2 

1/2 

1/2 

2/2 


TL-1345 
(1st sample) 

Sc.W. 


0.025 

0.05 

0.1 

0.15 

0.2 


G. pig 

0/2 

1/2 

2/2 

... 

... 



Rabbit 

0/2 

2/2 

1/2 

4/4 




Dog 

0/2 

1/2 

1/2 

2/2 




Cat 

. . . 

0/2 

1/2 

2/2 

2/2 



Monkey 



0/2 


3/3 

SB-8 

TL-599 

Sc.W. 


0.1 

0.2 

0.3 




Rat 


3/6 

6/6 





Rabbit 


1/3 

2/3 


. . • 



G. pig 

1/4 

4/5 

5/5 

. • . 

. . . 



Dog 

0/2 

2/3 

3/5 

. . . 

• . . 



Cat 


0/3 

2/2 




XI. Benzene compounds with one carbamate group and an alkyl side chain having a quaternary ammonium group. 


Code 


Name 


Route 

and Dose 

Structure solvent Species mg/kg Effect 


T-1180 Carbamic acid, N-methyl-2- 
dimethylaminomethyl- 
phenyl ester methiodide 


AR-39 Carbamic acid, N,N-dimethyl- 
2-d iethylaminomethyl- 
phenyl ester hydrochlo- 
ride 


AR-40 Carbamic acid, N,N-dimethyl- 
2-diethylaminomethyl- 
phenyl ester methiodide 


OCONHCH 3 Sc. 



Mice 7.2 LDso 

Rabbit 3.5 


Mice 1.5 Z/Dso 


Mice 0.5 LDso 


SECRET 


236 


AROMATIC CARBAMATES 


Table 2, Section XI {Continued) 


Code 


Name 


Route 

and 

Structure solvent 


Dose 

Species mg/kg Effect 


T-(?) Carbamic acid, N-methyl-N- 
( N'-methylcarbamyl )-2-di- 
methylaminomethylphenyl 
ester methiodide 


CHj 


OCON 


CONHCHa 

|CH2N(CH3)2T 


Sc. 


Mice 


343 


LD, 


T-2065 Carbamic acid, N-methyl-2- 
( 1-dimethylamino-n-pro- 
pyl)phenyl ester methiodide 


T-2068 Carbamic acid, N-methyl-2- 
( 1-dimethylamino-n-pro- 
pyl)phenyl ester hydro- 
chloride 


T-1890 Carbamic acid, N-methyl-2- 
dimethylaminomethyl-6- 
methylphenyl ester hydro- 
chloride 


OCONHCH3 

/\cHCH2CH3 




'N(CH3)3l 
OCONHCH3 
/\cHCH2CH3 




^N(CH3)2-HCi 
OCONHCH3 

CHaf Vh2N(CH3)2-HC1 


Sc. 


Sc. 


Mice 


Mice 


Mice 


10 


40 


350 


LA 


LDs 


LD, 


T-1891 Carbamic acid, N-methyl-2- 
dimethylaminomethyl-5- 
methylphenyl ester hydro- 
chloride 


CHa 


OCONHCH3 
1 CH 2 N(CH 3 ) 2 -HC 1 


Mice 


150 


LD, 


T-1892 Carbamic acid, N-methyl-2- 
dimethylaminomethyl-4- 
methylphenyl ester hydro- 
chloride 


T-1893 Carbamic acid, N-methyl-2- 
dimethylaminomethyl-4- 
methylphenyl ester meth- 
iodide 


T-1847 Carbamic acid, N-methyl-2- 
( a-dimethylaminoethyl )-4- 
methylphenyl ester hydro- 
chloride 


T-1846 Carbamic acid, N-methyl-2- 
( a-dimethylaminoethy 1 )-4- 
methylphenjd ester meth- 
iodide 


T-1824 Carbamic acid, N-methyl-3- 
( dimethylaminomethyl)- 
phenyl estor hydrochloride 


OCONHCH3 

j^CH2N(CH3)2-HCl 

CH3 

OCONHCH3 

j^CH2N(CH3)3l 

CH3 

OCONHCH3 

0 CHN(CH3)2HC1 

CH 3 

CH3 

OCONHCH3 

0 CHN(CH3)3l 

CH3 

CH3 

OCONHCH3 

I JcH2N(CH3)2-HC1 


Mice 


Mice 


Mice 


Mice 


Mice 


140 


75 


70 


12 


10 


LD, 


LD, 


LD, 


LD, 


LD, 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


237 




Table 2, Section XI {Continued) 







Route 







and 


Dose 


Code 

Name 

Structure 

solvent 

Species 

mg/kg 

Effect 


T-1825 Carbamic acid, X-methyl-3- 
( di methylaminomethy 1 )- 
phenyl ester methiodide 


OCONHCH 3 

JcH2N(CH3)3l 


Mice 


(«-dimethylaminopropyl)- 
phenyl ester hydrochloride 


T-1895 Carbamic acid, N-methyl-3- 
(a-dimethylaminopropyl)- 
phenyl ester methiodide 


AR-29 Carbamic acid, N-methyl-3- 
(a-dimethylaminoethyl)- 
6-methoxyphenyl ester 
hydrochloride 


AR-30 Carbamic acid, N-methyl-3- 
( a-dimet hylaminoet hy 1 )-6- 
methoxyphenyl ester 
methiodide 


T-1886 ? Carbamic acid, N-methyl-3- 
T-1938 ? (/3-dimethylaminoethyl)- 

phenyl ester hydrochloride 


T-2040 Carbamic acid, N-methyl-3- 
(2-dimethylamino-n-propyl )- 
phenyl ester hydrochloride 


T-2064 Carbamic acid, N-methyl-3- 

( 2-dimethylamino-n-propyl )- 
phenyl ester methiodide 


CHaOf 


CHaOl 


JCHN(CH3)2-HC1 
C 2 H 5 

OCONHCH 3 

]cHN(CH3)3l 
C 2 H 5 

OCONHCH 3 

]cHN(CH3)2'HC1 
CH 3 

OCONHCH 3 

]cHN(CH3)3l 
CH 3 
OCONHCH 3 


Mice 


Iv. 


Mice 


Iv. 


Mice 


JCH2CH2N(CH3)2-HC1 

OCONHCH 3 Sc. 

N(CH3)2-HC1 
^CH2CHCH3 


Mice 

Mice 


Mice 


LD, 


T-1887 ? 

Carbamic acid, N-methyl-3- 

OCONHCH 3 

? 

Mice 

100 

LD 30 

T-1939 ? 

( /3-dimet hy laminoethyl )- 
phenyl ester methiodide 

1 lcH2CH2N(CH3)3l 

? 

Mice ca. 

7.5-10 

LD^o 

AR-28 

Carbamic acid, N-methyl-3- 

OCONHCH 3 

Iv. 

Mice 

1.0 

LD$o 

T-1843 

(a-dimethylaminoethyl)- 

A 

Iv. 

Mice 

0.5 

LDio 


phenyl ester hydrochloride I 

1 1 

Sc. 

Rabbit 

1.0 ± 0.5 

LDio 


(miotine) I 

JcHN(CH3)2-HC1 


G. pig 

1.0 ± 0.5 




1 


Rat 

1.0 ± 0.5 




CH 3 


■ Mice 

• 1.0 ± 0.5 


T-1894 

Carbamic acid, N-methyl-3- 

OCONHCH 3 

? 

Mice 

3.0 

LDio 


5.0 LD, 


LD, 


LD, 


OCONHCH 3 

]cH2CHN(CH3)3l 
CH 3 


Sc. 


Mice 


35 LD 50 

Approx. 3.0 LDso 


Approx. 16 LDs 


0.6 LDio 


SECRET 


238 


AROMATIC CARBAMATES 


Table 2, Section XI (Continued) 


Code Name 


Route 

and Dose 

Structure solvent Species rng/kg Effect 


T-2038 


T-2039 


T-1845 


T-1844 


AR-28a 


T-1896 


T-1834 


AR-41 


AR-42 


T-1935 


Carbamic acid, N-methyl-3- 
(3-dimethylamino-n-butyl)- 
phenyl ester hydrochloride 


Carbamic acid, N-methyl-3- 
( 3-dimethylamino-n-butyl )- 
phenyl ester methiodide 


Carbamic acid, N-methyl-4- 
dimethylaminomethyl- 
phenyl ester hydrochloride 


Carbamic acid,N-methyl-4- 
( a-dimethylaminoethyl )- 
phenyl ester hydrochloride 


Carbamic acid, N-methyl-4- 
(a-dimethylaminoethyl )-2- 
methoxyphenyl ester hydro- 
chloride 


Carbamic acid, N-methyl-4- 
(a-dimethylaminopropyl )- 
phenyl ester methiodide 


Carbamic acid, N-methyl-4- 
( /3-dime thylaminoethyl )- 
phenyl ester hydrochloride 


Carbamic acid, N,N-dimethyl- 
4- ( /3-dimethylaminoethyl )- 
phenyl ester hydrochloride 


Carbamic acid, N,N-dimethyl- 
4-( /3-dimethylaminoethyl )- 
phenyl ester methiodide 


Carbamic acid, N-methyl-4- 
( 7-dimethylaminopropyl)- 
phenyl ester hydrochloride 


OCONHCH 3 Sc. 

A. N(CH3)2HC1 

CH 2 CH 2 CH 


CH 3 

OCONHCH 3 Sc. 

) N(CH3)3l 

CH 2 CH 2 CH 

CH 3 

OCONHCH 3 ? 


CH2N(CH3)2HC1 
OCONHCH 3 ? 


0 

CH3CHN(CH3)2HC1 

OCONHCH 3 Iv. 

j^OCH3 

CH3CHN(CH3)2HC1 

OCONHCH 3 ? 


CH3CH2CHN(CH3)3l 

OCONHCH 3 ? 



CH2CH2N(CH3)2-HC1 
0C0N(CH3)2 Iv. 



CH2CH2N(CH3)2HC1 

0C0N(CH3)2 Iv. 



CH2CH2N(CH3)3l 

OCONHCHa 



Mice 9 LD50 


Mice 10 LD50 


Mice 60 LDso 


Mice 25 LDso 


Mice 1-1.5 LDso 


Mice 300 LD50 


Mice 10 LD50 


Mice 15 LDso 


Mice 55 LDso 


Mice 5-7.5 LDso 


CIl2CH2CH2N(CH3)2 • HCl 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


239 


Table 2, Section XI (Continued) 


Code 


Name 


Structure 


Route 

and 

solvent 


Species 


Dose 

mg/kg 


Effect 


T-1936 Carbamic acid, N-methyl-4- 
( 7 -dimethylaminopropyl)- 
phenyl ester methiodide 


OCONHCH 3 


? 


Mice 


Approx. 50 LDf, 


T-1981 Carbamic acid, N-methyl-4- 
( 7 -dime thylamino-n-butyl )- 
phenyl ester hydrochloride 


CH2CH2CH2N(CH3)3l 

OCONHCH 3 


Sc. 


Mice 


100 


LDk 


T-1982 Carbamic acid, N-methyl-4- 
( 7 -dimethylamino-n-butyl )- 
phenyl ester methiodide 


CH2CH2CHN(CH3)2-HC1 

CH 3 

OCONHCH 3 


Sc. 


Mice 


40 


LDfi 


TIi-1415 Carbamic acid, N,N-dimethyl- 
3-(/3-2-pyridylethyl)phenyl 
ester methiodide 


CH2CH2CHN(CH3)3l 
CH 3 

0C0N(CH3)2 



Sc.W. 


Mice 


0.33 
(78 F) 


LD50 


T-1827 


T-1826 


T-1809 

T-1811 


T-1810 


AR-27 


XII. Benzene compounds with one carbamate group and two quaternary ammonium groups. 


Carbamic acid, N-methyl-2,4- 
6is( dimethylamino)phenyl 
ester dihydrochloride 


Carbamic acid, N-methyl-2,4- 
6Is( dimethylamino )phenyl 
ester dimethiodide 


0" 


OCONHCH 3 
N(CH3)2-HC1 


N(CH3)2-HC1 
OCONHCH 3 

A. 


A 


N(CH3)3l 


Carbamic acid, N-methyl-2,5- 
5zs(dimethylamino)phenyl 
ester dihydrochloride 

(CH3)2N-HC1| 


N(CH3)3l 

OCONHCH 3 

'1N(CH3)2-HC1 


Carbamic acid, N-methyl-2,5- 
6Ls(dimethylamino)phenyl 
ester dimethiodide 


Carbamic acid, N-methyl-3- 
[methyl-(/3-diethylamino- 
ethyl)-amino]phenyl ester 
hydrochloride 


OCONHCH 3 

0 N(CH3)3l 

OCONHCH 3 


? 


Iv. 


JnCH2CH2N(C2H5)2-HC1 

CH 3 


Mice 


Mice 


Mice 


Mice 


60 


LD, 




50-75 LD, 


Mice 500-1,000 LD^i 


0.1 




SECRET 


240 


AROMATIC CARBAMATES 


Table 2, Section XII {Continued) 


Code 


Name 


Route 

and Dose 

Structure solvent Species mg /kg Effect 


T-1780 


T-1779 


T-1833 


Carbamic acid, N-methyl-4- 
[methyl-(/3-diethylamino- 
ethyl)-amino]phenyl ester 
dihydrobromide 


Carbamic acid, N-methyl-4- 
[methyH /3-diethylamino- 
ethyl)-amino]phenyl ester 
monomethiodide 


Carbamic acid, N-methyl-5- 
dimethylamino- 2 -dimethyl- 
aminomethylphenyl ester 
dihydrochloride (CH 3 ) 2 - 


OCONHCH3 ? 



CH3— N— CH 2 CH 2 N(C 2 H 5)2 • HBr 
OCONHCH3 ? 



CHn— N— CH 2 CH 2 N(C 2 H 5)2 

OCONHCH3 ? 

0 CH2N(CH3)2-HC1 


Mice 16 LD^q 


Mice 100 LDsn 


Mice 500-2,500 LD 50 


TL-1306 


TL-1452 


TL-1479 


TL-1504 


TL-1459 


XIII. Benzene compound with one carbamate group and one sulfonium or arsonium group. 


Carbamic acid, N-methyl-3- 
methylthiophenyl ester 
methosulfate 


OCONHCH 3 Sc.W. Mice 0.370 LD 50 

(^S(CH3)2S04CH3 


Carbamic acid, N-methyl-2- 
dimethylarsinophenyl ester 
methiodide 


Carbamic acid, N,N-dimethyl- 
3-dimethylarsinophenyl 
ester methiodide 


Carbamic acid, N-methyl-3- 
diethylarsinophenyl ester 
methiodide 


Carbamic acid, N,N-dimethyl- 
4-dimethylarsinophenyl 
ester methiodide 


OCONHCH3 

|^As(CH3)3l 

0C0N(CH3)2 

(^As(CH3)3l 

OCONHCH3 



AS(CH3)3I 


Sc.W. Mice 


Sc.W. Mice 


Sc.W. Mice 


Sc.W. Mice 


80 

1/2 

40 

0/2 

20 

0/2 


10 

2/2 

5 

2/2 

1 

2/2 

0.5 

0/2 

1.0 

2/2 

0.5 

2/2 

0.25 

0/2 

0.125 

0/2 

80 

0/2 

40 

0/2 

20 

0/2 


TL-1096 


TL-1053 


XIV. Carbamates of naphthalene derivatives. 


Carbamic acid, N-methyl-2,4- 
dinitro-l-naphthyl ester 


Carbamic acid, N-methyl-1,6- 
dinitro-2-naphthyl ester 


OCONHCH3 Sc.P. 



Mice 


Mice 


80 

40 

20 


40 

20 

10 


2/2 

0/2 

0/2 


1/2 

0/2 

0/2 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


241 




Table 2, Section XIV {Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


T-1889 Carbamic acid, N-meth3d- 
5,6,7,8-tetrahydro-5-di- 
methylamino-2-naphthyl 
ester methiodide 


T-1888 Carbamic acid, X-methyl- 
5,6,7,8-tetrahydro-5-di- 
methylamino-2-naphthyl 
ester hydrobromide 


TL-1406 Carbamic acid, N-methyl- 
5 ,6 , 7, 8- te trahy dro-4-di- 
methylamino-l-naphthyl ester 
methiodide 


Mice 



N 


(CH3)2-HBr 

OCONHCH3 Sc.W. Mice 



N(CH3)3l 


20 LD^o 


4.0 LD50 


0.31 LD50 
(74 F) 


XV. Carbamates of quinoline and isoquinoline derivatives. 

T-1934 Carbamic acid, N-methyl-8- 

quinolinyl ester hydro- 
chloride 

CH3NHCO -HCl 

II 

O 

AR-37 Carbamic acid, N,N-dimethyl- 

8-quinolinyl ester hj^dro- 
chloride 

(CH3)2NC0 -HCl 




AR-18 

T-(?) 


AR-38 


T-1972 


T-1973 


Carbamic acid, N-methyl-8- 
quinolinyl ester methiodide 


Carbamic acid, N,N-dimethyl- 
8-quinolinyl ester metho- 
sulfate 


O 



II CH3SO4CH 
O 


Carbamic acid, N-methyl-1- 
methyl-l,2,3,4-tetrahydro- 
7-quinolinyl ester hydro- 
chloride 


Carbamic acid, N-methyl-1- 
methyl-1 ,2,3,4-tetrahydro- 
7-quinolinyl ester meth- 
iodide 




Iv. 

Mice 

0.1 

LDso 

Iv. 

Mice 

10 

LDio 

Sc. 

Mice 

90 

LDso 

Sc. 

Mice 

31 

LD^q 

(In buffer 




solution) 




Iv. 

Mice 

0.5 

LDio 


Mice 30 LD^o 


IMice 0.33 LD^o 


SECRET 


242 


AROMATIC CARBAMATES 




Table 2, Section XV {Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


T-1937 


T-1970 


Carbamic acid, N-methyl-1- 
methyl-1 ,2,3,4-tetrahydro- 
8-quinolinyl ester meth- 
iodide 


Isoquinoline, 2'methyl- 
1 ,2,3,4-tetrahydro-5,6-6is- 
( N -me thy Icarbamy loxy ) 
hydrochloride 



CH3NHCO2 


CHsNHCOaf 


sA 


s NCH,-HCI 


A 


? 


? 


Mice Approx. 45 LD50 


Mice 20 LDso 


T-1971 


T-1968 


T-1969 


Isoquinoline, 2-methyl- 

1 .2.3.4- tetrahydro-5,6-62.s- 
( N -methylcarbamyloxy ) 
methiodide 

Isoquinoline, 2-methyl- 

1 .2.3.4- tetrahydro-6,7- 
6is(N-methylcarbamyl- 
oxy) hydrochloride 

Isoquinoline, 2-methyl- 
1 ,2,3,4-tetrahydro-6,7- 
6is(N-methylcarbamyl- 
oxy) methiodide 


CH3NHCO2 
CH3NHCO2 



CH3NHCO2 

CH3NHCO2 


sA 


N(CH,), I 


CHsNHCOj^^ 

CH3NHC0J 


s NCHa-HCl 


® N(CH3)3l 

A 


? 


? 


? 


Mice 60 LD50 


Mice Approx. 400- LDso 
800 

Mice >800 


XVI. Carbamates of aliphatic alcohol derivatives. 


TL-1251 

Carbamic acid, 2-(dibutyl- 

I(C4H9)3NCH2CH20C0NH2 

Sc.W. 

Mice 

80 

0/2 


amino)-ethyl ester buto- 




40 

0/2 


iodide 




20 

0/2 

TL-1224 

Carbamic acid, N-methyl-2- 

I(C4H9)3NCIl2CH20C0NHCH3 

Sc.W. 

Mice 

80 

0/2 


(dibutylamino)-ethyl ester 




40 

0/2 


butoiodide 




20 

0/2 

TL-1234 

Carbamic acid, 2-(diethyl- 

I(C2H5)3NCH2CH20C0NH2 

Sc.W. 

Mice 

80 

0/2 


amino)-ethyl ester ethio- 




40 

0/2 


dide 




20 

0/2 

TL-1152 

Carbamic acid, N,N-di- 

I(C2H5)3NCH2CH20C0N(CH3)2 

Sc.W. 

Mice 

80 

0/2 


methyl-2-diethylamino- 




40 

0/2 


ethyl ester ethiodide 




20 

0/2 

TL-1151 

Carbamic acid, N-methyl-2- 

I(C2H5)3NCH2CH20C0NHCH3 

Sc.W. 

Mice 

80 

0/2 


diethylaminoethyl ester 




40 

0/2 


ethiodide 




20 

0/2 



CH2CH20CONHCH3 

Sc.W. 

Mice 

80 

0/2 

TL-1154 

Carbamic acid, N-methyl-2- 




40 

20 

0/2 

0/2 


piperidylethyl ester 






methiodide 

CH3I 





TL-1235 

Carbamic acid, 3-(dibutyl- 

I(C4H9)3NCH2CH2CH20C0NH2 

Sc.W 

Mice 

80 

0/2 


amino)-propyl ester buto- 




40 

0/2 


iodide 




20 

0/2 

TL-1225 

Carbamic acid, N-methyl- 

I(C4H9)3NCH2CH2CH20C0NHCH3 

Sc.W. 

Mice 

80 

0/2 


3-(dibutylamino)-propyl 




40 

0/2 


ester butoiodide 




20 

0/2 

TL-1215 

Carbamic acid, N-methyl- 

I(C5Hn)3NCH2CH2CH20C0NHCH3 

Sc.W. 

Mice 

80 

0/2 


3-(diamylamino)-propyl 




40 

0/2 


ester amyliodide 




20 

0/2 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


243 


Table 2 , Section XVI {Continued) 



Route 






and 


Dose 


Code 

Name 

Structure solvent 

Species 

mg/kg 

Effect 



CH 3 




TL-1252 

Carbamic acid, 2 -( diamyl- 

I(C5Hi03NCHCH2OCONH2 Sc.W. 

Mice 

80 

0/2 


amino )-propyl ester 



40 

0/2 


amyliodide 



20 

0/2 

TL-1399 

Propane, 1 -diethylamino- 

I Sc W. 

Mice 

80 

0/2 


2,3-6zs(N-methylcarba- 

CH3(C2H5)2NCH2CHCH20C0NHCH3 


40 

0/2 


myloxy)-, methiodide 

OCONHCH 3 


20 

0/2 

TL-1514 

Hexyne, 2,5-6is(N-methyl- 

C— CH(CH3)0C0NHCH3 Sc.P. 

Mice 

80 

0/2 


carbamyloxy)- 

Ill 


40 

0/2 


high melting form 

C— CH(CH3)0C0NHCH3 


20 

0/2 

TL-1515 

Hexyne, 2,5-h/s(N-methyl- 

C— CH(CH3)0C0NHCH3 Sc.P. 

Mice 

80 

0/2 


carbamyloxy)-low melt- 

Ill 


40 

0/2 


ing form 

C— CH(CH3)0C0NHCH3 


20 

0/2 

T-(?) 

Carbamic acid, N-benzyl- 

I(CH 3 ) 3 NCH 2 CH 20 CQNHCH 2 <^^^ ^ Sc. 




2 -dimet hylaminoethyl 
ester methiodide 

Mice 

6.25 

LD 50 

T-(?) 

Carbamic acid, N,N-di- 

/"= 0 > 

Mice 

75 

LD 50 

benzyl- 2 -dimet hyl- 
aminoethyl ester 





methiodide 

I(CH 3 ) 3 NCH 2 CH 20 C 0 N 





\ h .<0 


T-(?) 

Carbamic acid, 3-di- 
methylaminopropyl 
ester methiodide 

I(CH3)3NCn2CH2CH20C0NH2 

Sc. 

Mice 

37.5 

LD 50 

T-(?) 

Carbamic acid, 4-di- 
methylaminobiityl 
ester methochloride 

C1(CH3).3N(CH2)3CH20C0NH2 

Sc. 

Mice 

12.5 

LD^o 

T-(?) 

Carbamic acid, 10-di- 
methylaminodecyl 
ester methochloride 

C1(CH3)3N(CH2)9CH20C0NH2 

Sc. 

Mice 

75 

LD 50 

T-1096 * 

Carbamic acid, 5-di- 
methylaminoamyl 
ester methochloride 

C1(CH3)3N(CH2)4CH20C0NH2 

Sc. 

Mice 

20 

LD 50 

T-1124 

Carbamic acid, N-methyl- 
4-dimethylaminobenzyl 
ester methochloride 

C 1 (CH 3 ) 3 N<^ ^CH 20 C 0 NHCH 3 

Sc. 

Mice 

79 

LD 50 

T-(?) 

Carbamic acid, N-methyl- 
2 -dimethylaminoethyl 
ester methochloride 

C1(CH3)3NCH2CH20C0NHCH3 

Sc. 

Mice 

15 

LD^o 

T-(?) 

Carbamic acid, N,N-di- 
me thyl- 2 -di me thy 1 - 
aminoethyl ester 
methiodide 

I(CH3)3NCH2CH20C0N(CH3)2 

Sc. 

Mice 

20 

LDio 

T-(?) 

Carbamic acid, N-ethyl- 
2 -dimethylaminoethyl 
ester methochloride 

C1(CH3)3NCH2CH20C0NHC2H5 

Sc. 

Mice 

60 

LD 50 

T-(?) 

Carbamic acid, N,N-di- 

I(CH3)3NCH2CH20C0N(C2H5)2 

Sc. 

Mice 

42.5 

LD^o 


ethyl- 2 -dimethyl- 
aminoethyl ester 
methiodide 


SECRET 


244 


AROMATIC CARBAMATES 


Table 2, Section XVI {Continued) 


Code 

Name 

Structure 

Route 

and 

solvent 

Species 

Dose 

mg/kg 

Effect 



H 2 H 2 





T-(?) 

Carbamic acid, N,N-penta- 
methylene- 2 -dimethyl- 
aminoethyl ester 
methiodide 

C— C Sc. 

/ \ 

I(CH 3 ) 3 NCH 2 CH 20 C 0 N CH 2 

\ X 

c— c 

Mice 

4 

LDso 



H 2 H 2 





T-(?) 

Carbamic acid, N-allyl- 
2 -dimethylaminoethyl 
ester methochloride 

C1(CH3)3NCH2CH20C0NHCH2CH= 

= CH 2 

Sc. 

Mice 

37.5 

LDio 

T-(?) 

Carbamic acid, N-phenyl- 
2 -dimethylaminoethyl 
ester methiodide 

I(CH3)3NCH2CH20C0NHC6H5 

Sc. 

Mice 

450 

LD^o 

T-1093 

Morpholine, N-(/3-carba- 
myloxyethyl)-, 
methochloride 

Cl 

CH 3 — N— CH 2 CH 2 OCONH 2 

X \ 

Sc. 

Mice 

175 

LD50 


CH2 CH2 


CH2 CH2 

\ x/ 

O 

XVII. Miscellaneous Carbamates. 


TL-1380 

Physostigmine salicylate 


CH3 


Sc.W. 

Mice 

0.370 

LD50 


CH3NHCOO 

f' 

V 1 



Rats 

1.500 

0/2 


II 1 II 



G. pigs 

1.500 

0/2 



V 




Rabbits 

1.500 

0/2 





Cats 

1.200 

2/2 








1.000 

2/2 




CH3 CH3 




0.800 

2/2 




•C7H6O3 



Dogs 

1.400 

1/2 








1.200 

1/2 








1.000 

0/2 

AR-44 

Physostigmine salicylate 




Iv. 

Mice 

0.5 

LD^o 

AR-45 

Physostigmine methiodide 




Iv. 

Mice 

0.75-1.0 

LDsi) 

TL-1400 

Ammonium compound, substi- 


CH2 

Sc.P. 

Mice 

80 ' 

0/2 


tuted dimethyl- [i 8 -(N- 


/ 




40 

0/2 


methy Icarbamyloxy )- 7 -( 3,4- 


0 




20 

0/2 


me thy lenedioxy phenyl )pro- 


/ 0 






pyl] (3,4-methylenedioxy- 
benzyl) iodide 



CH2 


SECRET 


CHEMICAL STRUCTURE AND TOXICITY 


245 




Table 2, Section XVII {Continued) 




Code 

Name 

Route 

and 

Structure solvent 

Species 

Dose 

mg/kg 

Effect 


TL-1411 Carbamic acid, N-methyl- 
3-diniethylamino-d-bornyl 
ester methiodide 


AR-43 Carbamic acid, N-methyl ester 
of Harmol hydrochloride 


SB-25 Carbamic acid, N,N-dimethyl- 
i3-pyridyl ester hydrochlo- 
ride 



Mice 


Mice 


Mice 


80 

40 

20 


66 


120 


0/2 

0/2 

0/2 


LDso 


LDso 


TL-1517 Carbazic acid, 2,2-dimethyl-5- 
dimethylamino-2-methyl- 
phenyl ester dimethiodide 


TL-1516 Carbazic acid, 2,2-dimethyl- 
5-dimethylamino-2-methyl- 
phenyl ester dihydrochloride 


XVIII. Carbamides and carbazates. 

0C0NHN(CH3)3 Sc.W, 



0C0NHN(CH3)2 Sc.W, 

0 -2HC1 

N(CH3)2 


Mice 


Mice 


80 

40 

20 


80 

40 

20 


0/2 

0/2 

0/2 


0/2 

0/2 

0/2 


AR-26 Carbazic acid, 2-phenyl-3-di- 
methylaminophenyl ester 
methiodide 


OCONHNHCeHs Iv. Mice 0.25 LD,o 

(^N(CH3)a 


TL-1402 Urea, l-(4-hydroxy-2,3,5-tri- 
methylphenyl )-3-methyl- 


TL-1401 Benzene, l,4-5zs 

(1,3-dimethylureido)- 


H— N— CONHCH 3 

/\CH3 


CH3i^C4l3 

OH 

CH 3 — N— CONHCH 3 


CH 3 — N— CONHCH 3 


Sc.P. Mice 80 

40 

20 


Sc.W. Mice 80 

40 

20 


0/2 

0/2 

0/2 


0/2 

0/2 

0/2 


SECRET 


Chapter 14 


MISCELLANEOUS COMPOUNDS PREPARED OR EXAMINED AS 
CANDIDATE CHEMICAL WARFARE AGENTS 

By Marshall Gates 


14.1 INTRODUCTION 

I N TABLE 1 of this chapter are grouped all those 
compounds which for one reason or another have 
not been subjected to detailed toxicological examina- 
tion. With the average example, these substances 
showed insufficient toxicity to be seriously considered 
as chemical warfare agents, although other consider- 
ations, such as limited availability, instability, or 
lack of means for tactical employment have influ- 
enced decisions to abandon exploration of some com- 
pounds or the classes to which they belong. 

Several of the compounds included or classes cov- 
ered have been treated in other chapters of this vol- 
ume. For example, cadmium, cadmium oxide, other 
cadmium compounds, some selenium derivatives, and 
several metallic carbonyls form the subject of Chap- 
ter 11. The tabulation of this chapter is intended to 
supplement such chapters by including references to 
the preparation and screening of the less promising- 
members of such classes for the sake of completeness. 

Although a number of compounds examined by the 
British have been included in the tabulation, no at- 
tempt has been made to give comprehensive coverage 
to British screening tests, since such systematic lists 
are provided elsewhere. 

Perhaps worthy of mention in passing is the sub- 
stance dichloroformoxime (“phosgene oxime’’)- It 
was examined in this country because intelligence 
reports and published literature indicated that some 
attention had been paid it by the Germans and per- 
haps by the Russians. Dichloroformoxime possesses 
marked irritating action against skin which is mani- 
fested by an immediate burning sensation and the 
production of blisters. For this reason, the substance 
has been proposed as a “nettle” gas, but its limited 
stability, relatively low toxicity, and difficult prepa- 
ration preclude serious consideration of it as a chem- 
ical warfare agent. 

Dichloroformoxime exists when pure as a colorless 
solid of mp 39-40 C. It boils at 129 C without decom- 


position at atmospheric pressure and at 47-49 C 
at 23 mm and is soluble in water and in organic 
solvents. It is rapidly destroyed by alkalies and is 
slowly hydrolyzed by water.®^ It possesses a pene- 
trating and unpleasant odor and attacks the mucous 
membranes and the eyes severely.®^ The substance 
appears to be reasonably stable when pure and kept 
from contact with moisture or when stored in 
anhydrous ether solution but crude material rap- 
idly decomposes on standing. 

Three distinct methods of preparation are de- 
scribed in the open literature : 

1. The reduction of trichloronitrosome thane by 
hydrogen sulfide or aluminum amalgam,^ 

2. The action of chlorine on fulminic acid or on 
mercury fulminate,®^ 

3. The chlorination of chloroisonitrosoacetone.®® 

The first and third of these methods have been 

briefly examined by investigators under Division 9 of 
the National Defense Research Committee [NDRC] 
with disappointing results.^^^-^^^ The first gave rise to 
unspecified yields of material of poor quality which 
decomposed extensively in less than a day; the 
second gave only 30-40 per cent yields of crude ma- 
terial. The material which was examined physiologi- 
cally by the University of Chicago Toxicity Labora- 
tory melted below 35 C, and it is doubtful whether 
a pure sample of dichloroformoxime has been pre- 
pared or exammed in this country. 

The chlorination of fulminic acid salts has been in- 
vestigated briefly in England. The yields obtained 
(24-45 per cent) did not approach those claimed by 
Birckenbach and Sennewald.®^ It was found that 
twice recrystallized material is considerably more 
stable than distilled material and can be stored for 
several weeks without undergoing appreciable de- 
composition. 

The related dibromoformoxime has also been pre- 
pared and screened for toxicity.®®^ It is less toxic than 
the prototype. 


246 


SECRET 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


247 


Table 1. Miscellaneous compounds prepared or examined as candidate chemical warfare agents. 

The compounds in Table 1 are arranged in two large groups: (1) derivatives of heavy metals; and (2) miscellaneous 
organic compounds. Within the heavy metals group, the compounds are classified according to the periodic group of the 
metal, and, among each group of the periodic table, according to increasing atomic number. The miscellaneous organic 
compounds have been arranged according to the Beilstein system. 


The following abbreviations are used: refractive index at ^C; specific gravity at h C in reference to water at 

fo C; mp, melting point in C; bp^, boiling point in C at p mm Hg; vp^ vapor pressure in mm Hg at t C; voB, saturation 
concentration (volatility) in mg/1 at t C; and dec. p., decomposition point. 

British reports concerned with those compounds marked by an asterisk are not all available in this country. 

Centigrade scale is used throughout the table. 


Compound 

Reference 

to 

synthesis 

Refer, to 

Physical properties toxicity 

Property Reference data 

1. 

Cupric fluoroacetate 

52 


51 

2. 

Cupric 2,4-dinitrobenzenearsonate 

40a 



3. 

Cupric 2,4,6-trinitrobenzenearsonate 

40a 

... .... 

... ... 

4. 

Silver nitrate 

Commercial 

• • • .... 

24 

5. 

Zinc fluoborate 

40r 


24 

6. 

Zinc fluosilicate 

40q 

. • • .... 

24 

7. 

Strontium fluoborate 

40r 



24 

8. 

Strontium fluosilicate 

40r 


24 

9. 

Cadmiumf 

Commercial 


See Chap. 1 1 

10. 

Cadmium fluoridef 

40o 

... .... 

24 

11. 

Cadmium chloridef 

Commercial 


24 

12. 

Cadmium nitrate f 

Commercial 

... .... 

24 

13. 

Cadmium oxide f 

. • • 

... • • • . 

24 

14. 

Cadmium sulfide f 

Commercial 

\ 

24 

15. 

Cadmium selenide 

22 

... .... 

24 

16. 

Cadmium selenite 

40q 

... .... 

24 

17. 

Cadmium selenatef 

22 

... .... 

24 

18. 

Cadmium phosphite 

. . . 

... .... 

24 

19. 

Cadmium phosphate f 

. . . 

... .... 

24 

20. 

Cadmium fluoborate f 

40p 

... .... 

24 

21. 

Cadmium fluosilicate f 

40q 

dec.p. Approx. 100° 

40q 24 

22. 

Cadmium lactate 

6 

... .... 


23. 

Cadmium butyrate 

• • • 



24. 

Cadmium caproate 

6 



25. 

Cadmium palmitate 

6 

... .... 


26. 

Cadmium oleate 

6 

... .... 


27. 

Cadmium stearate 

6 

... .... 


28. 

Cadmium naphthenate 

6 

... .... 


29. 

Cadmium oxalate 

6 

... .... 


30. 

Cadmium malonate 

6 

... . • . • 


31. 

Cadmium maleate 

6 

... .... 


32. 

Cadmium fumarate 

6 

... .... 


33. 

Cadmium succinate 

6 

... .... 


34. 

Cadmium malate 

6 



35. 

Cadmium tartrate 

6 

... .... 


36. 

Cadmium glutarate 

6 



37. 

Cadmium adipate 

6 



38. 

Cadmium mucate 

6 



39. 

Cadmium citrate 

6 



40. 

Cadmium chelate of acetylacetone 

6 

dec.p. 280-285° 

6 

41. 

Cadmium enolate of ethyl nitromalonate 

6 

... .... 


42. 

Cadmium salt of nitrated oxidized starch 

Commercial 

... .... 

24 

43. 

Cadmium salt of 2,4-dinitrophenol 

6 

... .... 


44. 

Cadmium picrate 

6 

dec.p. 250° 

6 

45. 

Cadmium chelate of dinitroresorcinol 

6 

• . . .... 


46. 

Cadmium styphnate 

6 

... .... 


47. 

Cadmium w-nitrobenzenesulfonate 

6 

... .... 


48. 

Cadmium 2,4-dinitrobenzenesulfonate 

Cadmium p-nitrobenzoate 

6 

... .... 


49. 

6 

... .... 


50. 

Cadmium 2,4-dinitrobenzoate 

6 

... .... 


51. 

Cadmium 3,5-dinitrobenzoate 

6 

— 



t These compounds are discussed more fully in Chapter 11. 


SECRET 


248 MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


Table 1 {Continued) 



Reference 




Refer, to 



to 


Physical properties 

toxicity 


Compound 

synthesis 


Property 

Reference 

data 

52. 

Cadmium 2,4,6-trinitrobenzoate 

6 





53. 

Cadmium chelate of salicylaldehyde 

6 

mp 

>300° 

6 


54. 

Cadmium chelate of salicylaldoxime 

6 

mp 

>300° 

6 





dec. 

p. 280°-290° 

6 


55. 

Cadmium salicylate 

6 


. . . • 



56. 

Cadmium 3-nitrosalicylate 

6 


.... 

. . . 


57. 

Cadmium 5-nitrosalicylate 

6 



. . . 


58. 

Cadmium phthalate 

40k 

. . . 


. . . 


59. 

Cadmium o-nitrocinnamate 

6 

. . • 

• . • • 



60. 

Cadmium m-nitrocinnamate 

6 

. . . 

.... 

. . . 


61. 

Cadmium p-nitrocinnamate 

6 


.... 



62. 

Cadmium salt of hexanitrodiphenylamine 

6 

. • . 

.... 

. . . 


63. 

Cadmium o-nitrobenzenearsonate 

6 

• • * 

.... 



64. 

Cadmium 2,4~dinitrobenzeneai’Sonate 

6 

• • • 





65. 

Cadmium 2,4,6-trimtrobenzenearsonate 

6 






66. 

Cadmium 3,5-dimtro-4-hydroxybenzeneareonate 

6 


.... 

... 


67. 

Cadmium 3,5-dinitro-2,4-dihydroxybenzene- 







arsonate 

6 

• • • 

.... 



68. 

Cadmium furoate 

6 

• • • 





69. 

Cadmium 5-nitro-2-furoate 

6 

• • • 





70. 

Cadmium dehydromucate 

6 

• • • 

• • • • 



71. 

Cadmium 5-nitro-2-furylacrylate 

6 


.... 

. . . 


72. 

Cadmium chelate of 8-hydroxy quinoline 

6 

mp 

>325° 

6 


73. 

Dimethylcadmium 

6 

bp 

98-99° 

6 


74. 

Diethylcadmium 

6 

bp^" 

62-64° 

6 


75. 

Dipropylcadmium 

6 

bp*’ 

67° 

6 

• . • 

76. 

Barium fiuoborate 

40p 

mp 

>200° 

40p 

24 

77. 

Barium fluosilicate 

40p 

mp 

>200° 

40p 

• . • 

78. 

Barium succinate 

. . . 

• • • 

.... 


79. 

Barium salt of 2,4-dinitrophenol 

40e 

. . . 


• • « 


80. 

Barium 3,5-dinitrobenzoate 

40e 

• • • 

.... 



81. 

Barium 2,4,6-trinitrobenzoate 

40e 

• • • 

.... 



82. 

Barium salt of dipicrylamine 

40e 

• . . 

.... 

• • . 


83. 

Barium 2,4-dinitrobenzenearsonate 

40a 

• • • 




84. 

Barium 2,4,6-trinitrobenzenearsonate 

40a 

. . . 

.... 

. . . 


85. 

Barium 5-nitro-2-furoate 

40e 

• • • 




24 

86. 

Barium 5-nitro-2-furylacrylate 

40e 

• « • 

.... 



87. 

Mercuric chloride 

Commercial 

. . • 

.... 


24 

88. 

Mercuric fluoroacetate 

52 




51 

89. 

Mercury salt of nitrated oxidized starch 

Commercial 

• • • 




24 

90. 

Mercuric 2,4-dinitrobenzenearsonate 

40a 

• • • 





91. 

Mercuric 2,4,6-trinitrobenzenearsonate 

40a 






92. 

Chlorovinylmercuric chloride 

40j 


.... 


24, 33 

93. 

Butylmercuric iodide 

40e 



• . . 


94. 

Butylmercuric hydroxide 

40e 

. . • 




95. 

2-Chloromercurif uran 

28 

mp 

151-152.5° 

28 

24, 33 

96. 

2,5-( Dichloromercuri )f uran 

28 



24 

97. 

2-Chloromercurithiophene* 

28 

mp 

183-184° 

28 

24, 33 

98. 

2 , 5 - 62 s(Chloromercuri)thiophene* 

• • . 

. . . 

* • • « 

• . • 


99. 

Difurylmercury 

40e 

. . . 

.... 

* • . 

24, 33 

100. 

Thallous fluoride 

15 

bp 

298° 

15 

24 



. . . 

mp 

288° 

15 


101. 

Thallous fiuoborate 

15 

bp* 

300° 

15 

24 

102. 

Thallous selenite 

40r 




103. 

Thallous fluosilicate 

15 

bp* 

340° 

15 

24 

104. 

Thallous ethoxide 

15 





105. 

Thallous /3-chloroethylmercaptide 

40p 

mp 

>300° 

40p 


106. 

Thallous formate 

15 

• • • 

.... 


107. 

Thallous acetate 

15 




24 

108. 

Thallous fluoroacetate 

52 




51 

109. 

Thallous trifluoroacetate 

40p 

mp 

116-119° 

40p 

24 

110. 

Thallous salt of ethyl nitromalonate 

40c 


— 



SECRET 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


249 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

111. 

Thallium salt of nitrated oxidized starch 

Commercial 




24 

112. 

Thallous benzoate 

15 





113. 

Thallous p-nitrobenzoate 

15 





114. 

Thallous 2,4-dinitrobenzoate 

15 





115. 

Thallous 3,5-dinitrobenzoate 

15 





116. 

Thallous m-trifluoromethylbenzoate 

40p 




24 

117. 

Thallous salt of 2,4,6,2',4',6'-hexanitrodiphenyl- 







amine 

15 





118. 

Thallous furoate 

15 





119. 

Thallous 5-nitro-2-furoate 

15 





120. 

Thallous 5-nitro-2-furylacrylate 

15 





121. 

Thallous N-methyldithiocarbamate 

15 





122. 

Thallous N , N -dimethyldithiocarbamate 

15 

mp 

124-125° 

15 


123. 

Thallous N-ethyldithiocarbamate 

15 





124. 

Thallous N-isopropyldithiocarbamate 

15 





125. 

Thallous N,N-diethyldithiocarbamate 

15 

bp0.01-.02 

190° 

15 





mp 

110-111° 

15 


126. 

Thallous N-butyldithiocarbamate 

15 





127. 

Thallous N, N -diisopropyldithiocarbamate 

15 





128. 

Thallous N-cyclohexyldithiocarbamate 

15 





129. 

Thallous N,N-dibutyldithiocarbamate 

15 

bp0.01-.02 

230-235° 

15 





mp 

75-77° 

15 


130. 

Thallous N, N -diisobutyldithiocarbamate 

15 

mp 

165-165.5° 

15 


131. 

Dimethylthallium fluoride 

15 





132. 

Dimethylthallium iodide 

15 





133. 

Dimethylthallium hydroxide 

15 





134. 

Dimethylthallium fluoborate 

15 

mp 

303° 

15 


135. 

Dimethylthallium fluosilicate 

15 

mp 

>300° 

15 


136. 

Dimethylthallium ethoxide 

15 




24 

137. 

Dimethylthallium ethylmercaptide 





24, 33 

138. 

N-Dimethylthallium dimethylamine 

40i 





139. 

N-Dimethyl thallium diethylamine 

40i 





140. 

N-Dimethylthallium dibutylamine 

40i 





141. 

Dimethylthallium acetylacetone 

15 

mp 

214-215° 

15 


142. 

Dimethylthallium ethyl acetoacetate 

15 

mp 

128-130° 

15 


143. 

Dimethylthalhum trifluorohexoylacetone 





24, 33 

144. 

N-Dimethylthallium methylaniline 

40i 





145. 

Dimethylthallium salicylaldehyde 

15 

mp 

200°d 

15 


146. 

Dimethylthallium N,N-diethyldithiocarbamate 

15 

bpi 

130° 

15 

24, 33 




bp'* 

138° 

15 


147. 

Dimethylthallium N,N-diisopropyldithiocar- 

15 

bpi 

130° 

15 

24, 33 


bamate 









bp5.6 

145° 

15 





mp 

150° 

15 


148. 

Dimethylthallium N , N -dibutyldithiocarbamate 

15 

bpO.5 

147-148° 

15 


149. 

Dimethylthallium N,N-diisobutyldithiocarbamate 

15 

bpO.6 

104-105° 

15 

24 




mp 

73-74° 

15 


150. 

Diethylthallium bromide 

15 





151. 

Diethylthallium ethoxide 

15 





152. 

Diethylthallium trifluoroacetate 

15 

mp 

233-235° 

15 


153. 

Diethylthallium acetylacetone 

15 

dec.p. 

240° 

15 


154. 

Diethylthallium benzoylacetone 

40d 





155. 

Diethylthallium thioacetate 

15 

mp 

181-183° 

15 


156. 

Dipropylthallium ethoxide 

15 





157. 

Dipropylthallium-d-camphor-lO-sulfonate 

15 




15 

158. 

Diisopropylthallium chloride 

15 

mp 

150°d 

15 

15 

159. 

Dibutylthallium fluoride 

15 

mp 

220-230° 

15 

15 

160. 

Dibutylthallium chloride 

15 

mp 

240-245° 

15 

15 

161. 

Dibutylthallium bromide 

15 

mp 

245-250° 

15 

15 

162. 

Dibutylthallium iodide 

15 

mp 

220-225° 

15 

15 

163. 

Diisoamylthallium acetylacetone 

40d 





164. 

Diphenylthallium chloride 

40d 






SECRET 


250 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 


Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

165. 

Diphenylthallium iodide 

15 

mp 

>300° 

15 


166. 

Diphenylthallium hydroxide 

40d 





167. 

Difurylthallium fluoride 

15 

mp 

235-240°d 

15 


168. 

Difurylthallium iodide 

15 

mp 

238-240° 

15 


169. 

Tetramethylgermanium 





24 

170. 

Stannic 2,4-dinitrobenzenearsonate 

40a 





171. 

Stannic 2,4,6-trinitrobenzenearsonate 

40a 





172. 

Butyltin triiodide 

2 

bp® 

154° 

2 

2 

173. 

Dipropyltin dibromide 

2 

bpO.3 

112° 

2 

2 




mp 

49-50° 

2 

2 

174. 

Dibutyltin diiodide 

2 

bp5.6 

157° 

2 

2 

175. 

Di-^er/-butvltin dibromide 

2 

bpi^ 

128° 

2 

2 

176. 

6zs(2-Pyridyl)tin bromide 

40f 





177. 

Trimethyltin bromide 

2 

bp^ 

46-47° 

2 

2 

178. 

Trimethyltin hydroxide 

2 

sublim.p. 105-108° 

2 


179. 

Triethyltin hydride 

2 

bp® 

36° 

2 


180. 

Triethyltin bromide 

2 

bp 

216-217° 

2 

2, 24 

181. 

Tripropyltin hydride 

2 

bp2 

65° 

2 

24 





1.1452 

2 


182. 

Tripropyltin bromide 

2 

bp® 

123° 

2 

2, 24 

183. 

Triisopropyltin bromide 

2 

bp® 

79° 

2 


184. 

Triisopropyltin iodide 

2 

bp^ 

108-110° 

2 

2 

185. 

Tributyltin hydride 

2 

bp® 

115° 

2 

24 





1.108 

2 


186. 

Tributyltin chloride 

2 

bp^® 

119° 

2 

2 





1.134 

2 


187. 

Tributyltin bromide 

2 

bp® 

156° 

2 

2, 24, 33 

188. 

Tributyltin iodide 

2 

bp2 

138-139° 

2 

2, 24, 33 




di^^ 

1.501 

2 


189. 

Tributyltin cyanide 

2 

mp 

68° 

2 


190. 

Tributyltin thiocyanate 

2 

bpo.® 

160° 

2 

2 

191. 

Tributyltin hydroxide 

2 

^ 4 ^® 

1.160 

2 

2 

192. 

Tributyle thoxy t in 

2 

bpO.® 

105° 

2 

2, 24 





1.101 

2 


193. 

Tributylthioethoxytin 

2 

bpi® 

126° 

2 





d^^ 

1.132 

2 


194. 

Triamyltin bromide 

2 

bpi® 

162° 

2 

2 

195. 

Triisoamyltin bromide 

2 

bp® 

135° 

2 


196. 

Triisoamyltin iodide 

2 

bpi 

140-142° 

2 


197. 

Trihexyltin bromide 

2 

bp2 

194° 

2 

2 

198. 

Triphenyltinbenzenesulfonamide 

56b 

mp 

119° 

56b 

56b 

199. 

Tetramethyltin 

2 




24 

200. 

Tetraethyltin 

2 

bp 

176-180° 

2 


201. 

Tetrapropyltin 

2 

bp^® 

112° 

2 


202. 

Tetraisopropyltin 

2 

bp® 

116° 

2 


203. 

Tetrabutyltin 

2 





204. 

Tetraamyltin 

2 

bpi® 

181° 

2 


205. 

Tetraisoamyltin 

2 

bp24 

188° 

2 


206. 

Tetrahexyltin 

2 

bpi® 

209° 

2 


207. 

Tetradecyltin 

2 





208. 

Lead fluosilicate 

40q 

mp 

>200° 

40q 

24 

209. 

Lead salt of nitromethane 

1 





210. 

Lead salt of nitroaminoguanidine 

1 





211. 

Lead salt of dinitrotartaric acid 

1 





212. 

Lead-w-iiitroben zenesulfonate 

1 





213. 

Lead 2,4-dinitrobenzenesulfonate 

1 





214. 

Lead benzoate 

1 





215. 

Lead o-nitrobenzoate 

1 





216. 

Lead m-nitrobenzoate 

1 




• • • 

217. 

Lead p-nitrobenzoate 

1 





218. 

Lead 2,4-dinitrobenzoate 

1 





219. 

Lead 3,5-dinitrobenzoate 

1 






SECRET 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


251 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

220. 

Lead 2,4,6-trinitrobenzoate 

1 





221. 

Lead salt of p-nitrophenylhydroxamic acid 

1 





222. 

Lead salt of m-phenylenedinitroamine 

1 





223. 

Lead o-nitrobenzenearsonate 

1 





224. 

Lead m-nitrobenzenearsonate 

1 





225. 

Lead 2,4-dinitrobenzenearsonate 






226. 

Lead 2,4,6-trinitrobenzenearsonate 

1 





227. 

Lead 3-nitro-4-hydroxybenzenearsonate 

1 





228. 

Lead 3,5-dinitro-4-hydroxybenzenearsonate 

1 





229. 

Lead 3 , 5-dinitro-4- aminobenzenearsonate 

1 





230. 

Lead 5-nitrofiiroate 

1 





231. 

Lead 5-nitrofurylacrylate 

1 





232. 

Diethyllead dinitrate 

1 





233. 

Diethyllead selenite 

16 

mp 

>286° 

16 


234. 

Diethyllead 6zs(p-chlorobenzoate) 

16 

mp 

185°d 

16 


235. 

Diethyllead 6is( w-bromobenzoate ) 

16 

mp 

178-179°d 

16 


236. 

Diethyllead his{ m-nitrobenzoate ) 

16 

mp 

179-180°d 

16 


237. 

Diethyllead bis{p-io\uate) 

16 

mp 

186°d 

16 


238. 

Diethyllead bis{ N -butylanthranilate ) 

16 

mp 

169-169.5°d 

16 


239. 

Diethyllead dinicotinate 

16 

mp 

143°d 

16 


240. 

Diethyllead dithioacetate* 

56a 

mp 

84.5-85° 

56a 


241. 

Dibutyllead dinitrate 

1 





242. 

Diphenyllead dinitrate 

1 





243. 

s( m-N itrophenyl )lead dichloride 

1 





244. 

s( m-Nitrophenyl )lead dibromide 

1 





245. 

52s(w-Nitrophenyl)lead diiodide 

1 





246. 

bis{ m-N itrophenyl )lead din itrate 

1 





247. 

6fs(m-Nitrophenyl)lead oxide 

1 





248. 

Trimethyllead p-toluenesulfonate* 






249. 

Triethyllead thiocyanate* 

16 

mp 

26.5-27° 

16 

24, 33 

250. 

Triethyllead selenocyanate* 

16 

mp 

33-34° 

16 


251. 

Triethyllead nitrate 

1 





252. 

6is( Triethyllead) fluosilicate 





24 

253. 

Triethyl-/8-chlorothioethoxylead 

40m 




24 

254. 

Triethyllead fiuoroacetate 

56e 

mp 

180.5° 

56e 

55c 

255. 

Triethyllead a-chlorocrotonate 

16 

mp 

153-155° 

16 


256. 

Triethyllead acid oxalate 

16 

mp 

>300° 

16 


257. 

6is( Triethyllead) oxalate 

16 

mp 

>300° 

16 


258. 

6is( Triethyllead) fumarate 

16 

dec.p. 

165° 

16 


259. 

6fs( Triethyllead) adipate 

16 

mp 

>360° 

16 


260. 

fezs(Triethyllead) d-camphorate 

16 

mp 

>310° 

16 

16 

261. 

<m(Triethyllead) citrate 

16 

mp 

>350° 

16 


262. 

Triethyllead m-chlorobenzoate 

40d 





263. 

Triethyllead p-chlorobenzoate 

16 

mp 

123-124° 

16 


264. 

Triethyllead o-bromobenzoate 

16 

mp 

134-135° 

16 


265. 

Triethyllead m-bromobenzoate 

16 

mp 

113-114° 

16 

16 

266. 

Triethyllead p-bromobenzoate 

16 

mp 

127-128° 

16 


267. 

Triethyllead o-iodobenzoate 

16 

mp 

138.5-139° 

16 


268. 

Triethyllead m-iodobenzoate 

16 

mp 

135-136° 

16 


269. 

Triethyllead p-iodobenzoate 

16 

mp 

129.5-130.5° 

16 


270. 

Triethyllead o-nitrobenzoate 

16 

mp 

142-143°d 

16 

16 

271. 

Triethyllead m-nitrobenzoate 

16 

mp 

1 72-173°d 

16 


272. 

Triethyllead p-nitrobenzoate 

16 

mp 

167-168.5°d 

16 


273. 

Triethyllead salicylate 

16 

mp 

75-76° 

16 


274. 

Triethyllead p-anisate 

16 

mp 

97-98° 

16 


275. 

Triethyllead p-aminobenzoate 

16 

dec.p. 

265° 

16 


276. 

Triethyllead p-aminobenzoate monohydrate 

16 

mp 

84-86° 

16 


277. 

Triethyllead N -methylanthranilate 

16 

mp 

132.7°d 

16 


278. 

Triethyllead N-phenylanthranilate 

16 

mp 

124.5-125° 

16 


279. 

Triethyllead phenylacetate 

16 

mp 

96-97° 

16 


280. 

Triethyllead p-aminophenylacetate 

40d 





281. 

Triethyllead phenylpropiolate 

16 

mp 

149-150°d 

16 

16 


SECRET 


252 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

282. 

Triethyllead cinnamate 

16 

mp 

122-123°d 

16 


283. 

Triethyllead /S-benzoylacrylate 

16 

mp 

139-140°d 

16 


284. 

Trie thy Head 9-fluorenecarboxy late 

16 

dec.p. 

208° 

16 


285. 

Triethyllead |S( 2-napht hoyl )propionate 

16 

mp 

134-135° 

16 

16 

286. 

Triethyllead diphenylacetate 

16 

mp 

164-165° 

16 


287. 

Triethyllead triphenylacetate 

16 

mp 

134-136°d 

16 


288. 

Triethylleadsulfanilamide 

56b 

mp 

171° 

56b 

56b 

289. 

Triethyllead furoate 

16 

mp 

156-157°d 

16 


290. 

Triethyllead furylacrylate 

16 

mp 

132-133°d 

16 


291. 

Triethyllead lepidine-2-carboxylate 

16 

mp 

153-155° 

16 

16 




dec.p. 

197-199° 

16 


292. 

Triethyllead N-ethylcarbazole-3-carboxylate 

16 

mp 

195°d 

16 

16 

293. 

Triethyllead thioacetate* 

56a 

mp 

44° 

56a 


294. 

TriethyUead cyclohexylsulfinate 

16 

mp 

132-134° 

16 


295. 

Triethyllead p-toluenesulfinate 

16 

mp 

86-88° 

16 


296. 

Triethyllead o-toluenesulfonate* 

56a 

mp 

87° 

56a 


297. 

Triethyllead p-toluenesulf onate * 






298. 

Triethyllead 2-amino-5-toluenesulfonate 

16 

mp 

210°d 

16 


299. 

Triethyllead naphthalene-2-sulfonate* 






300. 

Triethyllead d-camphor-lO-sulfonate 

16 

mp 

172° 

16 

16 

301. 

Triethyllead p-tolylthiosulfonate 

16 

mp 

109° 

16 


302. 

Triethyllead methanesulfonamide* 

56b 

mp 

97° 

56b 

56b 

303. 

Triethyllead methanesulfonanilide* 

56b 

mp 

115.5° 

56b 

56b 

304. 

6zs(Triethyllead) methanedisulfonate 

56b 




56b 

305. 

5zs(Triethyllead) methanedisulfonanilide 

56b 




56b 

306. 

Triethyllead ethanesulfonanilide 

56b 

mp 

110° 

56b 

56b 

307. 

Triethyllead benzenesulfonamide 





55a 

308. 

Triethyllead p-aminobenzenesulfonamide 

16, 56b 

mp 

173-174° 

16 

56b 

309. 

Trie thy Head o- toluenesulf onamide * 

56b 

mp 

133° 

56b 


310. 

Triethyllead p-toluenesulf onamide * 





55a 

311. 

Triethyllead p-toluenesulfonanilide* 

56b 

mp 

134° 

56b 


312. 

Triethyllead p-toluenesuifon-p-chloranilide 

56b 

mp 

111.5° 

56b 

56b 

313. 

Triethyllead p-toluenesiilfon-p-bromanilide 

56b 

mp 

117° 

56b 

56b 

314. 

Triethyllead o-carboxybenzenesulfonimide* 

56b 

mp 

135° 

56b 


315. 

Tripropyllead o-toluenesulfonate 

56a 

mp 

87° 

56a 


316. 

Tripropyllead p-toluenesulfonate 

56a 

mp 

73-74.5° 

56a 


317. 

Triethyllead l-amino-4-naphthalenesulfonate 

16 

mp 

238-240° 

16 


318. 

Tripropyllead methanesulfonamide * 

56b 

mp 

67° 

56b 

56b 

319. 

Tripropyllead benzenesulfonamide 





55a 

320. 

Tripropyllead p-aminobenzenesulfonamide 

56b 

mp 

101° 

56b 

56b 

321. 

Tripropyllead p-toluenesulfonanilide 

56b 

mp 

104° 

56b 

55a 

322. 

Tripropyllead p-toluenesulfon-p-chloranilide* 

56b 

mp 

123° 

56b 

56b 

323. 

Tripropyllead o-carboxybenzenesulfonimide 

56b 

mp 

130° 

56b 

56b 

324. 

Tributyllead p-toluenesulfonate 

56a 

mp 

81-82° 

56a 


325. 

Tributyllead naphthalene-2-sulf onate 

56a 

mp 

68° 

56a 


326. 

Triphenyllead nitrate 

1 

mp 

220-225° 

1 





(sinter) 




327. 

Tri(m-nitrophenyl)lead chloride 

1 





328. 

Tri(m-nitrophenyl)lead nitrate 

1 





329. 

Tetramethyllead 





24 

330. 

Triethylallyllead dimer 

40h 


.... 



331. 

Antimony trifluoride 

Commercial 




24 

332. 

Ethyldichlorostibine 

13 

bpi 

62-83° 

13 

24 




d 

2.182 

13 


333. 

p-Thiocyanophenyldichlorostibine* 






334. 

p-Ethylthiophenyldichlorostibine* 






335. 

p-( /3-Chloroethylthio )phenyl dichlorostibine * 






336. 

p-Phenylenearsinestibine tetrachloride* 






337. 

6fs(w-Aminophenyl)chlorostibine dihydrochloride 





24 

338. 

his{ m- Aminopheny 1 )hy droxystibine 





24 

339. 

5, 1 0-Dichloro-5 , 1 0- dihydros tibarsanthrene * 






340. 

Diphenyl-a-thienylstibine* 







SECRET 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


253 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

341. 

Phenyldithienylstibine 

. . . 




... 

342. 

Trifurylantimony 

40e 




24, 33 

343. 

<m(5-f<>r/-Biityl-2-furyl)antimony 

40f 




24, 33 

344. 

fm(2-Pyridyl)antimony 

40g 




24, 33 

345. 

Trimethylstibine sulfide* 

. . . 




• . . 

346. 

6is(Trimethylstibo)trisulfide* 

. . . 




. . . 

347. 

6fs( Diphenylstibine )sulfide* 

. . . 




. . . 

348. 

Sulfate of 6ts(m-aminophenyl)hydroxystibine* 

. . . 




• . • 

349. 

5, lO-Dihydro-5, lO-dioxystibarsanthrene-5, 1 0- 







monoxide 

• . . 




. . • 

350. 

Diphenylbismuth thiocyanate* 

. . . 




56d 

351. 

tm( 2-Fury 1 )bismuth 

40f 




. . . 

352. 

Chromyl chloride 

28 

bp 

114° 

*28 

24 



* . . 


1.912 

28 

• . . 

353. 

Chromium hexacarbonyl 

40g 

. . . 

.... 

. . . 

. . • 

354. 

Chromium 5-nitro-2-furoate 

40c 

. . . 

... * 

• . . 

. • . 

355. 

Tungsten carbonyl 

36 

mp 

125° 

36 

35 



. . . 

vp67 

1.2 

36 

• . • 

356. 

Manganous 2,4-dinitrobenzenearsonate 

40a 

. . . 



. . . 

357. 

Iron pentacarbonyl* 

Commercial 




See Chap. 11 

358. 

Ferric 2,4-dinitrobenzenearsonate 

40a 

• . . 



. • . 

359. 

Cobaltous fluoborate 

. . • 

. . . 



24 

360. 

Salcomine 

Commercial 

. • • 



35 

361. 

Cobalt 2,4-dinitrobenzenearsonate 

40a 

• • • 



. . . 

362. 

Nickel carbonyl* 

. . . 

. . • 



See Chap. 11 

363. 

Nickel fluoborate 

40q 

. . . 



24 

364. 

Nickel fluosilicate 

40r 

mp 

>275° 

40r 

24 

365. 

Nickel 2,4-dinitrobenzenearsonate 

40a 

. . . 



. . . 

366. 

Chlorine 

Commercial 

. . • 



24, 59 

367. 

Bromine 

Commercial 

. . . 



24, 59 

368. 

Nitrogen fluoride 

. . . 

. . . 



24 

369. 

Ammonium fluoride 

Commercial 

. . . 



24 

370. 

Lithium hypochlorite 

. . . 

. . . 



24 

371. 

Hydrogen sulfide 

. . . 

mp 

-85.5° 

59 

59 



. . . 

bp 

-60.3° 

59 

. . . 

372. 

Sulfur monofluoride* 

54, 57 

bp 

-35° 

54 

54, 57 



. . . 


-99° 

• . . 

... 




mp 

-105.5° 

54 

• • • 




^-100 

1.5 

54 

• . • 

373. 

Sulfur tetrafluoride* 

54, 57 

bp 

-40° 

54 

54, 57 




mp 

-124° 

54 

• . • 

374. 

Sulfur hexafluoride 

• . . 

• . . 

.... 

• 

24 

375. 

Disulfurdecafluoride 

See Chap. 4 

• . , 

.... 


See Chap. 4 

376. 

Thionyl fluoride* 

54, 57 

bp 

-43.8° 

54 

24, 57 



. . . 

mp 

-129.5° 

54 

. . . 

377. 

Sulfuryl fluoride* 

54, 57 

bp 

-52° 

54 

24, 57 



. . . 

mp 

-120° 

54 

. . . 

378. 

Sulfuryl chlorofluoride 

• . . 

. . . 

.... 

. . . 

24 

379. 

Pyrosulfuryl chloride 

. . . 

. . . 

.... 

. . . 

24 

380. 

Hydrogen selenide 

. . . 

bp 

-41.5° 

59 

59 

381. 

Sodium selenide 

Commercial 

. . . 

.... 

• • . 

24 

382. 

Selenium monochloride f 

59 

bp733 

127° 

59 

59 



• • • 


2.7741 

59 




. * . 


1.5962 

59 

. • . 

383. 

Selenium monobromidef 


. . . 


. . . 

. . . 

384. 

Selenium hexafluoridef 

57 

sublim.p. 

-46.6° 

54 

57 

385. 

Carbon sulfideselenidef 




. . . 


386. 

Carbon diselenidef 

22 

bp 

117-118° 

22 

24 

387. 

Selenium oxychloridef 

23 

bp2i 

84-85° 

23 

24, 33, 59 



. . . 

mp 

10.9° 

59 

. . . 





1.6516 

59 



t These compounds and other selenium compounds are discussed more fully in Chapter 11. 


SECRET 


254 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

388. 

Selenium oxy bromide f 

• • • 





389. 

Selenium oxide 

Commercial 




24 

390. 

Selenium dioxide f 






391. 

Chloroselenious acidf 

. . • 





392. 

Sodium selenite 

• • • 




24 

393. 

Hydrazine hydrate 

Commercial 




24 

394. 

Ammonium fluosilicate 

Commercial 




24 

395. 

Trichloronitrosomethane 

7 




24 

396. 

Chloropicrin 

Commercial 

bp760 

112° 

65 

24 



. . . 

fp 

-69.2° 

65 

. • • 



* . . 

VoPO 

167 

26 


397. 

Diiodoacetylene 

27 

mp 

78-80° 

27 

24 

398. 

Nitroethylene 

Commercial 

. . . 

.... 


24, 33 

399. 

2-Propynyl chloride 

27 

bp 

58-65° 

27 

24, 33 





1.4405 

27 


400. 

1-Nitropropene 

Commercial 

voP® 

18.66 

26 

24 

401. 

2-Nitropropene 

Commercial 

VOpO 

64.14 

26 

24 

402. 

1 ,2-Dichloro-2-nitrosopropane 

7 

bp^^ 

41-42° 

7 

24 



. • . 


1.4323 

7 

. . . 



. . . 


1.239 

7 


403. 

1,1, l-Trichloro-3-nitro-2-propene 

18 

bpi 

44-45° 

18 

24, 33 



. . . 

mp 

-4.4° 

18 

. . . 



* . • 

ni?^ 

1.5172 

18 

• . • 



. . • 


1.5562 

18 

. . . 

404. 

2 -Bromo-2-nitrosopropane 

49a 

bpioo 

40° 

49a 

. . . 

405. 

2-Nitrobutene-l 

. . . 

VoPO 

32.36 

26 

24 

406. 

1 ,4-Dibromo-2-butene 

7 

mp 

54° 

7 

24, 33 

407. 

tris{ Chloromethyl )nitromet hane 

47a 

- . • 

.... 

. . . 

24, 33 

408. 

3-Chloro-3-nitrosopentane 

7 

bp38 

44° 

7 

24 



. . . 


1.4190 

7 

... 




di^^ 

1.016 

7 

• . * 

409. 

Methyl sulfite 

. . . 


.... 

. . . 

24 

410. 

Methyl silicate 

7 

bpl55 

75° 

7 

24 

411. 

Dimethyl selenide 

22 

bp 

56-58° 

22 

. . . 

412. 

Trimethylselenonium fluoride 

20 


1.378 

20 

24 





1.4600 

20 

. . . 

413. 

Dimethyl telluride* 


. • . 

.... 

. . . 

. . . 

414. 

Monochloromethyl sulfate* 


. . . 

.... 

. . . 

. . . 

415. 

6ts( Chloromethyl) sulfate* 


. . . 

.... 

. . . 

. . . 

416. 

6fs( Chloromethyl) ether* 


. . . 



• . . 

417. 

6fs(Bromomethyl) ether 

59, 401 

mp 

o 

CO 

1 

59 

24, 59 




bp 

154-155° 

59 

. . . 





2.2013 

59 

. . . 

418. 

/3-Chlorovinylselenium chloride* 

23 

mp 

86° 

23 

24 

419. 

Ethyl sulfite 


• . . 

.... 

. . . 

24 

420. 

Ethyl fluorosulfonate 


• . • 

.... 

. . . 

24 

421. 

Ethyl chloroselenite* 


. . • 

.... 

. . . 

. . . 

422. 

Ethyl selenomercaptan* 


. . . 

.... 

. . . 

. . . 

423. 

Ethoxyselenyl chloride* 


bp^® 

81.5-82.5° 

55e 

55e 

424. 

Diethyl selenide* 

22 

bp^® 

79-82° 

22 

24 

425. 

Diethyl diselenide* 


. . . 

.... 

. . . 

. . . 

426. 

Diethyl telluride 


. . . 

.... 


. . . 

427. 

im(iS-Chloroethyl) borate 

40s 

bp^ 

97-99° 

40s 

24 

428. 

tetrnkis{^-Ch\oroethy\) orthosilicate 

21 

bpi 

142-143° 

21 

24, 33 

429. 

jS-Chloroethyl nitrite 

7 

bp*° 

33° 

7 

24, 33 



. . . 


1.4115 

7 

. . . 



• • • 


1.212 

7 

. . . 

430. 

Methyl /3-chloroethyl sulfite* 

• • • 

• . . 

.... 

. . . 

24 

431. 

6fs(/3-Chloroethyl) sulfite* 

. . . 


.... 

. . . 

24, 33 

432. 

5fs(i8-Chloroethyl) selenite* 

. . . 

mp 

44-45° 

55e 

55e 

433. 

/3-Chloroethylsulfuryl chloride* 

12 

bpO.5 

60-64° 

12 

24 


t These compounds and other selenium compounds are discussed more fully in Chapter 11, 


SECRET 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


255 


Table 1 {Continued) 


Reference Refer, to 

to Physical properties toxicity 

Compound synthesis Property Reference data 


434. 6fs(/3-Chloroethyl) sulfate 

12 

bpO.6 

117-133° 

12 

24 

435. 6fs(/8-Chloroethyl) ether 

Commercial 

. • . 


. . . 

24, 33 

436, 6fs(/3-Chloroethyl) selenide* 

437. 6fs(/3-Chloroethyl) selenium dichloride* 

22 

bpo-i 

96-100° 

22 

24, 33 

438. 2-Propyn-l-ol 

27 

bp 

113-117° 

27 

24 

. . . 


1.4330 

27 

. • . 

439. 3-Bromo-2-propyn-l-ol 

27 

bp=^ 

49-53° 

27 

24 




1.5140 

27 

. - • 

440. 3-Iodo-2-propyn-l-ol 

27 

bp® 

82-85° 

27 

24, 33 

. . . 

mp 

40-43° 

27 


441. Methyl 2-propynyl ether 

27 

bp 

61-65° 

27 

24 


. . . 


1.4052 

27 

• . . 

442. Methyl 3-bromopropynyl-2 ether 

27 

bpi® 

34-38° 

27 

24 


. . . 


1.4793 

27 

. . . 

443. 3-Chloroallyl alcohol 

. . . 

. . . 

.... 

. . . 

24, 33 

444. Allyl methyl ether 

. . . 

. . . 

.... 


24 

445. siyw-Dichloroisopropyl chlorosulfinate 

32 

bp^® 

108-110° 

32 

24, 33 


. . . 


1.5130 

32 

. . • 


• . . 


1.432 

32 

• • • 

446. 2-Nitro-l -butanol silicate 

40b 

. . . 

.... 

. . . 

. . . 

447. Ethinyldimethylvinyl carbinol 

Commercial 

. . . 

.... 

. . . 

24, 33 

448. 2-Butyne-l,4-diol 

Commercial 


.... 

. . . 

24 

449. 5fs-/3-Chloroethyl formal 

12 

bp^2 

92-94° 

12 

24 

450. Methylformylchloride oxime 

19 

bp 

65-66° 

19 

24 



mp 

-64 to -60° 

19 

. . . 




1.4193 

19 

• . . 


• • • 


1.135 

19 

. . • 

451. Acetaldehyde azine 

7 

bp 

96-98° 

7 

3, 24 



1.4370 

7 

• . . 

452. Hemiacetal of chloral and chloretone 

47b 

mp 

68-69° 

47b 

. . . 

453. Chloral oxime 

7 

bp®9 

69-70° 

7 

24, 33 


• . • 


1.4905 

7 

. • . 


• . • 


1.571 

7 

. . . 

454. Acrolein 

Commercial 

. . . 

.... 

. . . 

24 

455. Propionaldehyde azine * 

7 

bp 

139-141° 

7 

3, 24 

. . . 


1.4497 

7 

• . • 

456. Acetone azine 

7 

bp 

129-133° 

7 

3, 24 


• • • 

no'® 

1.4511 

7 

. . • 

457. 6is(Selenoacetone)* 

. . . 

bp® 

.... 

. . . 

. . . 

458. Chloroacetone oxime 

7 

70-71° 

7 

24 


• • • 


1.4777 

7 

. . . 


• . . 

d^^ 

1.221 

7 

. . . 

459. Bromoacetone 

21 

bpi® 

35.5-36.5° 

21 

24 

460. Butyraldehyde azine 

7 

bpi7 

77-78° 

7 

3, 24 

. . • 


1.4504 

7 

. . . 

461. Methylethylketone azine 

7 

bp2i 

71-72° 

7 

3, 24 


. . . 


1.4517 

7 

. . . 

462. l-Bromobutanone-2 

21 

bp®® 

62-66° 

21 

24 


. . . 


1.4700 

21 

. . • 

463. 3-Bromobutanone-2 

21 

bp®® 

49-53° 

21 

24 


• • . 

no'® 

1.4595 

21 

. . . 

464, Selenovaleraldehyde* 

. • . 


.... 

. . . 

. . . 

465. Die thylke tone azine ' 

7 

bp2® 

94-96° 

7 

3, 24 

. . . 

no^® 

1.4539 

7 

. . . 

466. l-Bromopentanone-2 

467. 3-Bromopentanone-2 

21 

21, 58 

bp^® 

75-76° 

21 

24 

• . . 

nj)^^ 

1 .4576 

21 

. . . 


• . • 

voP® 

21.59 

26 


468. a-Chloromesityl oxide 

39 

bp®i 

66-69° 

39 

24 

469. l-Hydroxy-2-pentyne-4-one 

27 

bp® 

79-83° 

27 

24 


. . . 


1.4587 

27 

. . . 



voB® 

0.111 

26 

• . • 


SECRET 


256 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

470. 

l-Methoxy-2-pentyne-4-one 

27 

bp3 

47-50° 

27 

24, 33 





1.4462 

27 


471. 

Carbon suboxide 

38 




24 

472. 

1 , 1 ,4,4-Tetraethoxy-2-butyne 

27 

bp2 

97-102° 

27 

24 




nD^° 

1.4346 

27 


473. 

Diketene 


bp28 

43° 

38 

24 

474. 

Hydrocyanic acid 

See Chap. 2 




See Chap. 2 

475. 

Sodium cyanide 

Commercial 




24 

476. 

Triallyl orthoformate 





24 

477. 

2-Propynyl formate 

27 

bp 

105-109° 

’27 

24, 33 




/Id'®-" 

1.4203 

27 


478. 

Allyl formate 





24 

479. 

or, ^-Dichlorovinyl acetate 

49c 

bp^2 

41-43° 

49c 

24 

480. 

/3-Triazoethyl acetate 

21 

bp^o 

74° 

21 

24 





1.4345 

21 






1.123 

21 


481. 

Acetyl fluoride 

12 

bp 

20-22° 

12 

24 

482. 

Acetyl azide 

21 





483. 

Acetonitrile-boron trifluoride addition product 

39 

mp 

118-120° 

39 

24 

484. 

Methyl selenolacetate 

22 

bp^2 

29-31° 

22 





bp 

112-114° 

22 


485. 

Sodium chloroacetate 

Commercial 




24 

486. 

Chloroacetyl fluoride 

49n 

bp750 

36^2 

26 

24 




vopo 

74-76° 

49n 


487. 

Sodium bromoacetate 





24 

488. 

Bromoacetyl bromide 

Commercial 




24, 33 

489. 

Sodium iodoacetate 





24 

490. 

Ethyl iodoacetate 

40k 




24, 33 

491. 

Propiolic acid 

27 

bp35 

73-77° 

27 

24, 33 

492. 

Methyl propiolate 

27 

bp 

100-102° 

27 

24, 33 

493. 

Ethyl propiolate 

27 

bp 

119-120° 

27 

24, 33 

494. 

j8-Chloroethyl propiolate 

27 

bpi^ 

79-82° 

27 

24, 33 




nD^“ 

1.4588 

27 


495. 

Allyl propiolate 

27 

bp®° 

70-73° 

27 

24 





1.4378 

27 


496. 

Bromopropiolic acid 

27 

mp 

85.5-87° 

27 

24, 33 

497. 

Methyl bromopropiolate 

27 

bp“ 

40-45° 

27 

24 





1.4884 

27 


498. 

Acrylonitrile 

Commercial 

bp 

75.5-76° 


24 

499. 

Methyl a-chloroacrylate 

7 

bp5o 

51-55° 

7 






1.4400 

7 






1.201 

7 


500. 

j8-Chloroacrylonitrile 





24 

501. 

«,i3-Dichloroacrylonitrile 

Commercial 

bp®® 

58-59° 


24, 33 

502. 

a ,/3,/3-Trichloroacrylonitrile 

48 

mp 

17-19° 

48 

24 




bp740 

141-142° 

48 


503. 

Ethyl /8-chloropropioniminoester hydrochloride 

12 

mp 

96°d 

12 


504. 

Q:,a,/3-Trichloropropionitrile 





24 

505. 

Methoxytetrolic acid 

27 

bp3 

114-118° 

’27 

24, 33 





1.4669 

27 


506. 

Methyl methoxytetrolate 

27 

bp® 

56-58° 

27 

24, 33 





1.4438 

27 


507. 

Crotonyl fluoride 

49e 

bp 

88° 

49e 

24 

508. 

Ethyl vinylacetiminoester hydrochloride 

12 

mp 

90-100°d 

12 


509. 

Allyl cyanide 





24 

510. 

7 -Chlorocrotononitrile 

49m 

bpi® 

60-62° 

49m 

24 

511. 

/3-Chlorocrotononitrile 

48 

bp736 

125.5-126.5° 

48 

24 

512. 

Butyryl fluoride 

49e 

bp 

65-67° 

49e 

24 

513. 

Methyl a-chloroisobutyrate 





24 

514. 

a-Triazobutyric acid 

21 

bp®-^ 

80° 

21 

24, 33 





1.4536 

21 


515. 

Methyl a-nitro-/3-methylcrotonate 

49p 

bp24 

120-125° 

49p 



SECRET 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


257 


Table 1 {Continued) 


Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

516. Methyl methoxyacetate 





24 

517. Dimethyl diglycolate 

Commercial 




24 

518. 6is(/3-Chloroethyl) diglycolate 

7 

bp2 

195-199° 

7 


519. Formaldehyde cyanohydrin 





24 

520. Methyl 2,2,2-trichlorolactate 

49q 

bp* 

92-94° 

49q 

24 

521. Chloralcyanohydrin 

49h 

mp 

59-60° 

49h 


522. jS-Cyanoethyl nitrite 

49d 

cannot be distilled 

49d 


523 . 1-Chloro- 1 -isonitrosoace tone 

19 

mp 

108-109° 

19 

24, 33 

524. l-Chloro-2-methylgly oxime 

19 

mp 

183-184°d 

19 

24, 33 

525. Trichloroacetylcyanide 

49g 

bp 

118-121° 

49g 

24 

526. Vinyl mucochlorate 

Commercial 

VOpO 

0.289 

26 

24, 33 

527. Hexachlorodimethyl oxalato 

49h 

mp 

79-80° 

49h 

24 

528. Oxalyl fluoride 

10 

bp 

approx. 2-3° 

10 

24 

529. Oxalyl chloride 

12 

bp 

64-65° 

12 

24, 33 

530. Methyl cyanoformate 

42e 

bp 

98-99° 

42e 

24 

531. Chlorocyanoformaldoxime 

42d 

bp* 

53-54° 

42d 

24, 33 



mp 

54-56° 

42d 


532. Cyanogen 





24 

533. Diethyl dichloromalonate 

17 

bp^'* 

115-116° 

17 

24 



riD^® 

1.4386 

17 


534. Diethyl ethoxymethylenemalonate 

47c 

riD^” 

1.4600-1.4620 

47c 

24 

535. Ethoxymethylenemalononitrile 

49j 

mp 

60-63° 

49j 

24 

536. Diethyl diethoxymethylmalonate 

47d 

bp^* 

133° 

47d 

24 




1.4220 

47d 


537. Dimethyl acetylenedicarboxylate 

49e 

bp2o 

1.17 

26 

24* 33 



vopo 

98-99° 

49e 

. . # 

538. Diethyl acetylenedicarboxylate 

27 

bp* 

84-88° 

27 

24, 33 




1.4435 

27 


539. 6is(/3-Chloroethyl) acetylenedicarboxylate 

27 

bp^ 

175-215°d 

27 

24 



^dIs.s 

1.5004 

27 


540. Diallyl acetylenedicarboxylate 

27 

bp^ 

112-118° 

27 

k 




1.4718 

27 


541. Diisopropyl acetylenedicarboxylate 

27 

bp4 

103-107° 

27 

24 



^d18-6 

1.4408 

27 


542. 6is(2-Ethylhexyl) acetylenedicarboxylate 





24 

543. Dimethyl maleate 

27 

bp 

199-204° 

27 

24, 33 

544. Dimethyl fumarate 


bp 

189-192° 

27 

24, 33 

545. Diallyl fumarate 

27 

bp2“ 

137-140° 

27 

24 

546. Fumaryl chloride 

48 

bp^* 

62-63° 

48 

24 

547. Dimethyl chloromaleate 





24, 33 

548. Diethyl bromomaleate 

49g 

bpO.6 

85-86° 

49g 

24 

549. Diethyl chlorofumarate 

27 

bp2o 

137-139° 

27 

24, 33 

550. Chlorofumaronitrile 

Commercial 




24, 33 

551. Diethyl bromofumarate 

27 

bp* 

120-123° 

27 

24 

552. Chlorofumaryl chloride 

27 

bp210 

140-143° 

27 

24 

553. Dimethyl dibromomaleate 

17 

bpii 

134-136° 

17 

24 

554. Diethyl Qr,a:'-dichlorosuccinate 

17 

bp* 

106-108° 

17 

24 

555. Dimethyl Q:,Q:'-dibromosuccinate 

17 

mp 

60-61° 

17 

24 

556. Dimethyl tetrachlorosuccinate 





24 

557. Dimethyl a,Q;'-dichloroglutarate 

17 

bpi 

95-96° 

17 

24 

558. Dimethyl a,a:'-dichloroadipate 

17 

bp2 

126-128° 

17 

24 




1.4660 

17 


559. 5fs(Trichloromethyl) carbonate 





24 

560. Methyl /S-chloroethyl carbonate 





24, 33 

561. 6fs(/3-Chloroethyl) carbonate 

12 

bpi* 

119-122° 

12 

24 

562. Methyl fluorocarbonate 

49g 

bp 

43-45° 

49g 

24 

563. Methyl chlorocarbonate 





24 

564. Trichloromethyl chlorocarbonate (diphosgene) 

See Chap. 3 




See Chap. 3 

565. Ethyl chlorocarbonate 





24, 33 

566. /3-Chloroethyl chlorocarbonate 

7 

bp752 

152.5° 

7 

24 




1.4465 

7 





1.3825 

7 



SECRET 


258 MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 




Table 1 {Continued) 





Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

567. 

Allyl chlorocarbonate 

49f 

bp 

107-111° 

49f 

24 

568. 

Methyl triazoformate 

49i 

bp 

97-101° 

49i 

24 

569. 

Carbonyl chlorofluoride 

See Chap. 3 




See Chap. 3 

570. 

Carbonyl chloride (phosgene) 

See Chap. 3 




See Chap. 3 

571. 

N,N-Dichloroure thane 

49d 


• • . • 


24, 33 

572. 

Dimethyl azoformate 

7 

bp^® 

98° 

7 

24 




bp^ 

104° 

7 






1.4180 

7 






1.222 

7 


573. 

6fs(/3-Chloroethyl) azoformate 

7 

bp^ 

140-143° 

7 

33 





1.4752 

7 






1.390 

7 


574. 

Cyanogen chloride 

See Chap. 2 




See Chap. 2 

575. 

Dichloroformoxime (phosgene oxime) 

42a, 56c, 62, 

bp23 

47-49° 

42a 

24, 55b 



64, 66 

mp 

39-40° 

63 





bp 

129° 

63 


576. 

Cyanogen bromide 

Commercial 




24 

577. 

Dibromoformoxime 

55b 




55b 

578. 

Methyl chlorothiolformate 

42c 

bp 

111 - 112 ° 

42c 

24 





1.4901 

42c 






1.290 

42c 


579. 

Trichloromethyl chlorothiolformate 

42c 

bp26 

153-162° 

42c 

24 




no 

>1.52 

42c 






1.654 

42c 


580. 

Thiophosgene 

42c 

bp 

73-76° 

42c 

24 

581. 

Thiocarbonyl chloride polymer 

42c 




24 

582. 

Acetyl thiocyanate 

49h 

bp 8 i 

60.5-61.0° 

49h 

24 

583. 

Carbomethoxy isothiocyanate 

49h 

bp ^8 

58-61° 

49h 

24 

584. 

Methyl thiocyanate 

28 

bp^^® 

128-129° 

28 

24 





1.4681 

28 






1.0732 

28 


585. 

2-Chloroethyl thiocyanate 

5 




24, 33 

586. 

Hexyl thiocyanate 

28 

bpi -8 

84-87° 

28 

24 




nD 

1.5650 

28 






0.941 

28 


587. 

Dodecyl thiocyanate 

28 

bp ^8 

177-179° 

28 

24 




nj)^^ 

1.460 

28 





^2528 

0.8958 

28 


588. 

Ethylene dithiocyanate* 

28 

mp 

90.5-91.5° 

28 

24 

589. 

Q:,Q:-Dithiocyanopropane* 






590. 

6 ts(Isothiocyanomethyl) ether* 





24 

591. 

Acetonyl thiocyanate 

49e 




24 

592. 

Cyanogen sulfide* 






593. 

Methyl chlorodithioformate 

42c 

bpi 8 

47-49° 

42c 

24: 

594. 

Allyl selenourea* 






595. 

1,3- Diselenocyanopropane* 






596. 

Cyanogen diselenide* 






597. 

/S-Chloroetheneseleninyl chloride* 

23 




24 

598. 

Ethaneseleninic acid 

23 





599. 

Ethaneseleninyl chloride hydrate 

23 

mp 

72-75° 

23 

24 

600. 

N,N-Dimethylformamide 

Commercial 




24 

601. 

2,5-bis{ N-Methylcarbamyloxy )-3-hexy ne ( two 







forms) 





35 

602. 

N,N-Dimethylcarbamyl fluoride 

49k 

bp 88 

65° 

49k 

24 

603. 

Dimethylcarbamyl chloride 

11 

bp 

166-168° 

11 

24 

604. 

Methyl isocyanate 

37 

bp 

37-39° 

37 

35 

605. 

Dimethylsulfamyl fluoride* 

49n 

bpi 8 

48.5° 

49n 

24, 55d 

606. 

Dimethylsulfamyl chloride 

11 

bp“‘‘ 

34° 

11 

24, 33, 55d 

607. 

N,N-Diethylchloroacetamide 

Commercial 




24, 33 

608. 

N , N '-Diethyloxamide 

11 

mp 

175° 

11 

24 

609. 

Ethyl N,N- 62 :s(j 8 -chloroethyl) carbamate 

39 

bpii 

131-132° 

39 

24 





1.4688 

39 






1.214 

39 



SECRET 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


259 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

610. 

N-Butylmaleimide 






24 

611. 

Dibutylcarbamyl chloride 

11 

bp3 

108-109° 


11 

24,33 

612. 

4-Chloropentyldiethylamine hydrochloride 

34 

mp 

99.5-100° 


34 

24 

613. 

Ethylenediamine thiosulfate 






24 

614. 

1 ,6-Hexanediamine 

Commercial 





24 

615. 

1,6-Hexanediol diisocyanate 

Commercial 





24, 33 

616. 

/3-Dimethylaminoethyl formate 

14 

bp7« 

125-130° 


14 

24, 33 





1.4262 


14 






0.905 


14 


617. 

jS-Dimethylaminoethyl acetate 

14 

bp7« 

148-151° 


14 

24, 33 





1.4178 


14 






0.928 


14 


618. 

/3'Methylethylaminoethyl formate 

14 

bp^^^ 

147-150° 


14 

24, 33 





1.4287 


14 





^20^° 

0.919 


14 


619. 

jS-Methylethylaminoethyl acetate 

14 

bp^'^^ 

162-163° 


14 

24, 33 





1.4226 


14 





d2o2° 

0.918 


14 


620. 

Formylcholine chloride 

14 

mp 

144-146° 


14 

24 

621. 

Acetylcholine chloride 

Commercial 





24 

622. 

Carbaminoylcholine chloride (Doryl) 






35 

623. 

/3-(N-Methylcarbamyloxy)ethyltrimethylam- 








monium chloride 

49b 





24, 33 

624. 

/3-( N -Propylcarbamyl )choline iodide 






24 

625. 

/3-( N -Butylcarbamyl )choline iodide 






24 

626. 

/3-Diethylaminoethyi formate 

14 

bp7« 

157-160° 


14 

24, 33 





1.4358 


14 





^20^“ 

0.900 


14 


627. 

/3-Diethylaminoethyl acetate 

14 

bp62 

101-103° 


14 

24, 33 





1.4259 


14 





d2o2° 

0.911 


14 


628. 

/3-Diethylaminoethyl carbamate ethiodide 

29 

mp 

150-150.5° 


29 

24 

629. 

/3-Diethylaminoethyl N-methylcarbamate eth- 








iodide 

29 

mp 

90-92° 


29 

24 

630. 

jS-Dibutylaminoethyl carbamate butoiodide 

29 

mp 

99.5-100.5° 


29 

24 

631. 

/3-Dibutylaminoethyl N-methylcarbamate buto- 








iodide 

29 

mp 

100-101.5° 


29 

24 

632. 

his{ jS-Hy droxye thyl )methylamine 

Commercial 





24 

633. 

/3-Methylhydroxyethylaminoethyl formate 

14 

bp^ 

126-127° 


14 

24, 33 





1.4698 


14 





d2o2o 

1.045 


14 


634. 

Methyl-6fs(/3-formoxyethyl)amine 

14 

bp7 

110-111° 


14 

24, 33 





1.4501 


14 





d2o2« 

1.101 


14 


635. 

Methyl-6fs(j8-acetoxyethyl)amine 

46b, 46c 

bpO.6 

59-60° 


46b 

33, 35 





1.439 


46b 


636. 

his{ /3-Hy droxyethy 1 )ethylamine 

Commercial 





24 

637. 

7 -I)ibutylaminopropyl carbamate butoiodide 

29 

mp 

122.5-123.5° 


29 

24 

638. 

7 -Dibutylaminopropyl N-methylcarbamate buto- 








iodide 

29 

mp 

110.5-112° 


29 

24 

639. 

7 -Diamylaminopropyl carbamate amyliodide 

29 

mp 

108-110° 


29 

24 

640. 

7 -Diamylaminopropyl N -methylcarbamate 








amyliodide 

29 

mp 

78-83° 


29 

24 

641. 

l-Diethylamino-2,3-&fs(N-methylcarbamyloxy) 








methiodide 

29 

mp 

122-123.5° 


29 

24 

642. 

Ethyl diazoacetate 

21 

bp^2 

42-43° 


21 

24 





1.4592 


21 


643. 

Dimethylaminoacetonitrile 

’49h 

bp^i 

55-56° 


49h 

24 

644. 

tris{ /3-Thiocyanoe thyl )amine 






51 

645. 

Trifluoromethylsilicane 






24 

646. 

Trichloromethylsilicane 






24 

647. 

Dichlorodimethylsilicane 






24 


SECRET 


260 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


Table 1 {Continued) 


Reference Refer, to 

to Physical properties toxicity 

Compound synthesis Property Reference data 


648. Chlorotrimethylsilicane 





24 

649. Ethyl trifluorosilicane 





24 

650. Ethyltrichlorosilicane 

40n 

bp760 

96-98° 

40n 

24 

65 1 . Tetraethylsilicane 

40f 




24, 33 

652. Trifluoropropylsilicane 





24 

653. Trichloropropylsilicane 



.... 


24 

654. Trichloroisopropylsilicane 



.... 


24 

655. Butyl trifluorosilicane 




. . . 

24 

656. Butyltrichlorosilicane 





24 

657. Tributylboron 

40a 





658. Hexachlorocyclohexane (impure) 

Commercial 




24: 

659. Q;-Bromo-2-chloro-6-nitrotoluene 

Commercial 




24, 33 

660. 2-Nitro-l-phenylpropene 

18 

bpi® 

64.5-65.5° 

18 




mp 

139° 

18 

24, 33 

661. 1 ,2-bis{ jS-Chloroethyl )benzene 

32 

bp 

120-122° 

32 

24 

662,. Phenyl chlorocarbonate 





24, 33 

663. 2,4,6-Trichlorophenyl chlorocarbonate 





24, 33 

664. Picryl silicate 

40a 





665. Cyclohexyl dithiocyanate* 






666. o-Chlorophenyl thiocyanate* 





* 

667. m-Chlorophenyl thiocyanate* 






668. p-Chlorophenyl thiocyanate* 






669. o-Bromophenyl thiocyanate* 






670. Phenyl selenocyanate* 






671. o-Chlorophenyl selenocyanate* 






672. o-Nitrophenyl selenocyanate* 






673. p-Nitrophenyl selenocyanate* 






674. o-Tolyl thiocyanate* 






675. o-Tolyl selenocyanate* 






676. m-Tolyl selenocyanate* 






677. 0 -, m-f and p-Chlorobenzyl thiocyanates* 






678. Benzyl selenocyanate* 






679. o-Nitrobenzyl selenocyanate* 






680. 2,4-Dinitrobenzyl selenocyanate 






681. Benzylisothioiironium chloride 





24 

682. 3,5-Dimethyl-4-nitrosophenol 

31 

mp 

179°'d 

31 

24 

683. Pyrocatechol sulfite 





24 

684. 3-Allylpyrocatechol 

4 

bp^ 

104-115° 

"4 

24, 33 




1.5660 

4 





1.129 

4 


685. 4-Allylpyrocatechol 

4 

mp 

44.5° 

4 

24 

686. 3-(l-Vinylethyl-)pyrocatechol 

4 

bp® 

138-143° 

4 

24, 33 




1.5536 

4 





1.10 

4 


687. 3-Benzylpyrocatechol 

4 

bpO.l-0.2 

110-160° 

4 

24, 33 




1.5911 

4 




d26.62®-® 

1.141 

4 


688. 3-Cinnamylpyrocatechol 

4 

bp®-^ 

165-200° 

4 

24 



nj)^^ 

1.6045 

4 




dv^^ 

1.161 

4 


689. 3-Geranylpyrocatechol 

4 

bpO.06-0.1 

150-200° 

4 

24,33 




1.5440 

4 




^26^® 

1.031 

4 


690. 3-Tridecenylpyrocatechol 



.... 


24 

691. p-Anisyl selenocyanate* 






692. p-Phenetyl selenocyanate* 






693. p-Benzyloxyphenyl selenocyanate* 






694. p-Nitrobenzyloxyphenyl selenocyanate* 






695. p-Phenylene diselenocyanate* 






696. Leuconic acid 

*36 




24 

697. d-Camphorimine nitrate 

44d 

mp 

162-163°d 

44d 

24 


SECRET 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


261 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 


Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

698. 

N-Methyl-d-camphorimine 

44d 

bp3 

52-53° 

44d 

24 




bp 760 

203-204° 

44d 





wd 

1.4833 

44d 






0.9214 

44d 


699. 

d-Camphoroxime 

44e 

mp 

•119-120° 

44e 

24 




bp-" 

141° 

44e 


700. 

a-Chloroacetophenone 


. . . 



24 

701. 

a,a-Dichloroacetophenone 





24 

702. 

Q!,o-Dichloroacetophenone 





24 

703. 

a-Chloro-o-nitrosoacetophenone 

47e 

mp 

138°d 

*476 

. . . 

704. 

a-Chloro-p-phenylacetophenone 





24 

705. Phenylpropargyl aldehyde 

27 

bp^^ 

114-117° 

27 

24 





1.6029 

27 

. . . 

706. 

Phenylpropargyl acetal 

27 

bpi" 

153-156° 

27 

24 





1.5160 

27 


707. 

a-Bromopropiophenone 





*24 

708. Selenocyanoacetophenone* 






709. 

3-Isonitrosocamphor (d) 

44e 

mp 

154-155° 

44e 

24 




bp^" 

179° 

44e 


710. 

l,3,5-/ris(Chloroacetyl)benzene 

32 

mp 

148-150° 

32 

24, *33 

711. 

2-Methyl-l ,4-naphthoquinone 





24, 33 

712. 

m-N itrobenzoylazide 

21 

mp 

67-68° 

21 

24 

713. 

a-Bromobenzoylcyanide 

59 

mp 

29° 

59 

24, 59 




bp^^ 

132-134° 

59 


714. 

Methyl phenylpropiolate 

27 

bp2 

94-99° 

27 

24 




riD^® 

1.5612 

27 

. . . 

715. 

a-Amyl-N-(diethylaminoethyl)cinnamide hydro- 







chloride 

45 

mp 

102° 

45 

24 

716. 

/3-Benzoylpropionolactone 

49d 

mp 

89-90° 

49d 

24 

717. 

a-Chloro-o-cyanoacetophenone 

47f 

mp 

118-119° 

47f 

24 

718. 

N-Bromomethylphthalimide 

8 

mp 

147-150° 

8 


719. 

Benzylidenemalononitrile 

8 

mp 

82-83° 

8 

24, 33 

720. 

o-Chlorobenzylidenemalononitrile 

8 

mp 

94-95° 

8 

24, 33 

721. 

o-Brom obenzylidenemalononitrile 

8 

mp 

89.8-90.5° 

8 

24, 33 

722. 

m-N itrobenzylidenemalononitrile 

8 

mp 

104-105° 

8 

24, 33 

723. 

3-Methylamino-d-borneol hydrochloride 

43 




24 

724. 

/3-( N -Phenylcarbamyl )choline iodide 





24 

725. 

Tetranilinosilicon 

40h 





726. 

Phenylimidophosgene 


voP" 

1.85 

26 

24 

727. 

Hexanitrodiphenylamine 



— 


24 

728. 

Trimethyl(2-phenylaminoethyl) ammonium 







chloride 


. . . 

.... 

. . . 

24 

729. 

1 ,2 ,3,4-Tetrahy dro-N , N -dimethyl-2-naphthyl- 







amine methochloride 

41b 

mp 

221° 

41b 

24 

730. 

1,2, 3, 4-Tetrahydro-N,N-dimethyl- 2-naphthyl- 







amine methiodide 

41b 

mp 

222° 

41b 

24 

731. 

4-Dimethylaniino-3-isopropylphenol methiodide 





35 

732. 

m-( Diethylamino )phenol methochloride 

37 

mp 

180-182°d 

37 

24 

733. 

4,4 '-Dithiocyanodiphenylamine 





24, 33 

734. 

p-Selenocyanoaniline* 






735. 

p-Selenocyanodimethylaniline* 






736. 

N -V anillylmandelamide 

9 

mp 

105-106° 

9 

24, *33 

737. 

N-Vanillyl-lO-hendecenamide 

9 

mp 

60-61° 

9 

24, 33 

738. 

N-Methyl-N'-(4-hydroxy-2,3,5-trimethylphenyl)- 







urea 

30 

mp 

226-227° 

30 

24 

739. 

N,N'-Dicarbomethoxy-p-phenylenediamine 

49g 

mp 

207-209° 

49g 

24 

740. 

N,N'-Dicarbethoxy-p-phenylenediamine 

34 

mp 

192-193° 

34 

24 

741. 

N,N'-Dicarbethoxy-2,5-dichloro-p-phenylenedi- 







amine 

41a 




24 

742. 

N , N '-Dicarbethoxy-2 , 6-dichloro-p-phenylenedi- 







amine 

34 

mp 

178-180° 

34 

24, 33 


SECRET 


262 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


Table 1 {Continued) 




Reference 




Refer, to 



to 


Physical properties 

toxicity 


Compound 

synthesis 

Property 

Reference 

data 

743. 

N , N '-bis{ /3-Chlorocarbe thoxy )-p-pheny lenedi- 







amine 

34 

mp 

201° 

34 

24 

744. 

1 ,4-6 is{ N , N '-Dime thy liireido )benzene 

30 

mp 

229.5-230.5° 

30 

24 

745. 

N , N '-Disulfinyl-p-phenylenediamine 
p-Dirtiethylaminoaniline « 

46a 

mp 

115-116° 

46a 

35 

746. 

Commercial 




24,33 

747. 

p-Dimethylaminophenyl isothiocyanate 

34 

bp® 

148-150° 

34 

24 




mp 

69-70° 

34 


748. 

p-Dimethylaminophenyl isothiocyanate hydro- 







chloride 

34 

mp 

144-145° 

34 

24 

749. 

p-Dimethylaminophenyl isothiocyanate meth- 




• 



iodide 

34 

mp 

171° 

34 

24 

750. 

N-Methyl-N-(p-dimethylaminophenyl)thiourea 

hydrochloride 

N, S-Dimethyl-N '-( p-dimethylaminophenyl )- 





24 

751. 







thiourea hydroiodide 





24 

752. 

N,N'-Dimethyl-p-phenylenediamine 

34 

bpi7 

157-160° 

34 

24, 33 




mp 

53-54° 

34 


753. 

N,N '-Dimethyl-p-phenylenediamine dihydro- 
chloride 

34 

mp 

224°d 

34 

24 

754. 

N,N '-Dicarbethoxy-N,N '-dimethyl-p-phenyl- 







enediamine 

34 

mp 

106-107° 

34 

24 

755. 

N , N , N N '-Te tramet hy 1-o-pheny lenediamin e 

34 

bp^2 

92-93° 

34 

24, 33 

756. 

N , N , N ' ,N '-Tetrame thy 1-o-pheny lenediamine 
methiodide 

34 

mp 

194°d 

34 

24 

757. 

N , N , N N '-Tetrame thy 1-m-pheny lenediamine 

34 

bpio 

121-124° 

34 

24, 33 

758. 

N,N,N ',N '-Tetramethyl-m-phenylenediamine 
methiodide 

34 

mp 

187°d 

34 

24 

759. 

N , N , N ', N '-Tetrame thy 1-p-pheny lenediamine 

Commercial 




24, 33 

760. 

N , N ,N ', N '-Tetrame thy 1-p-phenylenediamine di- 







hydrochloride 

34 

mp 

222°d 

34 

24 

761. 

N , N , N ', N '-Tetramethy 1-p-pheny lenediam ine 







methiodide 

34 

mp 

266°d 

34 

24 

762. 

p-Phenylene-62s( oxazolidone-3 ) 

34 

mp 

253-254° 

34 

24 

763. 

N ',N '-Diethyl-N,N-dimethyl-p-phenylenediamine 34 

bp^“ 

137° 

34 

24, 33 




mp 

263-265° 

34 


764. 

N , N '-Die thy 1-N , N '-dimethyl-p-pheny lenedi- 






amine 

34 

bpi^ 

150-151° 

34 

24, 33 

765. 

N,N,N'-Triethyl-N'-methyl-p-phenylenediamine 

34 

bpi« 

144° 

34 

24, 33 




mp 

22° 

34 


766. 

N,N,N '-Triethyl-N '-me thy 1-p-pheny lenediamine 
dihydrochloride 

34 

mp 

220°d 

34 

24 

767. 

N , N, N '-Triethyl-N '-me thy 1-p-ph enylenedia mine 
methiodide 

34 

mp 

177° 

34 

24 

768. 

N,N,N ',N '-Tetraethyl-p-phenylenediamine 

34 

bpi4 

155-156° 

34 

24, 33 




mp 

51-52° 

34 


769. 

N , N , N ', N '-Tetraethy 1-p- pheny lenediamine 







methiodide 

34 

mp 

185° 

34 

24 

770. 

N,N'-6^s(^3-Hydroxyethyl)-p-phenylenediamine 

34 

mp 

123° 

34 

24 

771. 

N,N'-6is(l-Methyl-4-diethylaminobutyl)-p- 







phenylenediamine 

34 

bplO"® 

145° 

34 

24 

772. 

N-Methyl-N'-(p-dimethylaminomethylphenyl)- 







thiourea hydrochloride 





24 

773. 

Polymer of N,N'-decamethylene-N,N '-dimethyl- 







4, 4 '-diaminodiphenylmethane 6^s-metho- 
bromide 





24 

774. 

Phenylhydrazine 

Commercial 




24 

775. 

N-Carbomethoxy-N '-phenylhydrazine 

49f 

mp 

114.5-116° 

49f 

24 

776. 

p-Phenylenedihydrazine dihydrochloride 

34 

dec.p. 

200° 

34 

24 

777. 

Tetra-m-nitrophenylsi 1 icon 

40a 




24 

778. 

Tetrahydrofurfuryl alcohol 

Commercial 




24 

779. 

Tetrahydrofurfuryl fluorocarbonate 

49r 

bp®® 

92-94° 

49r 

24 

780. 

Tetrahydrofurfuryl chlorocarbonate 

49o 

bp^“ 

81-83° 

49o 



SECRET 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


263 


Table 1 {Continued) 

Reference Refer, to 

to Physical properties toxicity 



Compound 

synthesis 


Property 

Reference 

data 

781. 

3 ,6 -Epoxy cyclohexene 





24, 33 

782. 

Adduct of furan and maleic anhydride 

7 

mp 

110-111° 

7 

24, 33 

783. 

Furan 

Commercial 




24 

784. 

Methylfuran 

Commercial 




24 

785. 

1 -( 2-Furyl )-2-nit roethylene 

18 

bpio 

74-75° 

18 

24, 33 




mp 

110° 

18 


786. 

l-( 2-Furyl )-2-nitropropene 

18 

bpio 

48.5-49.5° 

18 

24, 33 




mp 

125° 

18 


787. 

Furfuryl alcohol 

Commercial 




24 

788. 

2-Furaldehyde 

Commercial 




24 

789. 

Furoic acid 

Commercial 




24 

790. 

5-Hydroxy-2-chloromethyl-7-pyrone 

12 

mp 

162-163° 

12 


791. 

5-Methoxy-2-chloromethyl-7-pyrone 

12 

mp 

119-120° 

12 

24 

792. 

5-Hydroxy-2-dimethylaminomethyl-7-pyrone 







methochloride 

49p 

mp 

245°d 

49p 

24 

793. 

Tetrafurylsilicon 





24 

794. 

Isobutylenimine 

32 

bp 

69-70° 

32 

24 

795. 

N -Isopropylet hylenimine 

32 

bp 

65.5-66.5° 

32 

24 

796. 

N-Phenylethylenimine 

32 




24 

797. 

Azetidine 

. . . 




24 

798. 

Heliotridenef 

25 

bp 

164-166° 

25 

24 





1.4870 

25 


799. 

Chlororetronecanet 

25 

bp3° 

111-112° 

25 

24 




nn'® 

1.4913 

25 


800. 

6(or 7)-Chloro-l-chloromethyl-l ,2-dehydropyro- 







lizidine hydrochloride J 

25 

mp 

122-123° 

25 

24 

801. 

Retronecanolf 

25 

mp 

93-95° 

25 

24 

802. 

Desoxyretronecine hydrochloride! 

25 

mp 

181-183° 

25 

24 

803. 

PlatynecineJ 

25 

mp 

147-148° 

25 

24 

804. 

Retronecinet 

25 

mp 

119-121° 

25 

24 

805. 

Monocrotaline! 

25 

mp 

199-201°d 

25 

24 

806. 

Diace tylretronecine t 

25 

bp”-i 

101-108° 

25 

24 

807. 

Diace tylretronecine methiodidej 

25 

mp 

122-123° 

25 

24 

808. 

2-Metliyloctahydropyrrocoline 

25 

bp2® 

70-72° 

25 

24, 33 





1.4667 



809. 

Octahydro-2,4-dimethylpyrrocolinium iodide 

25 

mp 

226-227° 

25 

*24 

810. 

4-Allyloctahydro-2-methylpyrrocolinium bromide 

25 

mp 

258-259°d 

25 

24 

811. 

Octaliydro-2-methyl-4-(/3-phenylethyl)-pyrro- 







colinium bromide 

25 



. . . 

24 

812. 

Octahy dro-4-(/3-hydroxyethyl )-2 -methylpy rro- 







colinium bromide 

25 


.... 


24 

813. 

4-(|3-Acetoxyethyl)-octahydro-2-methylpyrro- 







colinium chloride 

25 




24 

814. 

2-Triacetylnorcholyloctahydropyrrocoline 

25 

mp 

75-95° 

25 

24 

815. 

N -Chlorocarbamylpiperidine 





24 

816. 

/3-( Piperidyl-N-carbamyl )choline iodide 



.... 


24 

817. 

1-Piperidylsulfamyl chloride 





24 

818. 

N -/S-Hydroxyethylpiperidine 

12 

bp^" 

95-96° 

12 


819. 

2-Piperidyloethyl N-methylcarbamate 







methiodide 

29 

mp 

103-105° 

29 

24 

820. 

N-Cyanomethylpiperidine 

49h 

bp^i 

83-84° 

49h 

24 

821. 

2-Vinylpyridine 

12 




. . . 

822. 

Coniine (a-propylpiperidine) 

Commercial 




24 

823. 

2-( /3-Hy droxye thy 1 )pyri dine 

12 

bpO-2 

84-90° 

12 


824. 

3-Bromoacetylpyridine hydrobromide 





24 

825. 

Nicotine 

Commercial 




24 

826. 

2-(N-Carbomethoxyamino)pyridine 

49j 

mp 

122° 

49j 

24 

827. 

4-( |8-Dime thylaminoethyl )py ridine 

30 

bp2o 

135-145° 

30 

35 

828. 

4-(j8-Dimethylaminoethyl)pyridine dimethiodide 

30 

mp 

207-208° 

30 

35 

829. 

2-( jS-Hy droxye thy lamino )pyridine 

12 

bp^^ 

180-185° 

12 





mp 

109-110° 

12 



t These substances were obtained from natural sources. 


SECRET 


264 


MISCELLANEOUS COMPOUNDS AS CHEMICAL WARFARE AGENTS 


Table 1 {Continued) 



Compound 

Reference 

to 

synthesis 

Physical properties 

Property Reference 

Refer, to 
toxicity 
data 

830. 

2-Carbethoxyoxy-4-carbethoxyaminopyrindane 

34 

mp 

139-141° 

34 

24 

831. 

4-Carbethoxyamino-2-p-tosyloxy-4-pyrindane 

34 

mp 

132.5° 

34 

24 

832. 

4-Amino-2-hydroxypyrindine 


mp 

309° 

34 

24 

833. 

4-Acetylamino-2-hydroxypyrindine 





24 

834. 

2-Acetoxy-4-acetylaminopyrindine 





24 

835. 

2-Methylpyrrocoline hydrochloride 

25 

mp 

61-62° 

25 

24 

836. 

2-Phenylpy rrocol ine 

25 

mp 

214-215° 

25 

24 

837. 

3-Acetyl-2-methylpyrrocoline 

25 

mp 

83-85° 

25 

24 

838. 

2-Triacetylnorcholylpyrrocoline 

25 

mp 

169-170.5° 

25 

24 

839. 

1,2,3,4-Tetracarbomethoxyquinolizine 

25 

mp 

186-188° 

25 

24 

840. 

4,7-Dichloroquinoline 

47c 

mp 

84-85° 

47c 

24 

841. 

2-p-Nitrophenyl quinoline 

401 





842. 

8-Methoxy-5-methylquinoline 





24 

843. 

2-( m-Dimethylaminophenyl )quinoline 

40k 





844. 

2-( p-Dimethylaminophenyl )quinoline 





24, 33 

845. 

2-( p-Dimethylaminophenyl )-3-bromoquinoline 

40j 




24 

846. 

N-2-Naphthyl-l,2,3,4-tetraliydro-l,3-isoquino- 

linedione 

Commercial 




24 

847. 

9-V inylcarbazole 





24, 33 

848. 

Et hylene-N -nitrosourea 

19 

mp 

102-104°d 

19 

24 

849. 

l,4-Diethyl-l,4-6zs(/3-hydroxyethyl)piperazinium 

dichloride 





24 

850. 

2-Phenylimidazo-[l,2-a] pyridine hydrobromide 

25 

mp 

122-124° 

25 

24 

851. 

N -M orpholinoacetonitrile 

49i 

mp 

60° 

49i 


852. 

1 ,4-Selenoxan-4-dichloride* 






853. 

Phenoxtellurine * 






854. 

10, 10-Dichlorophenoxtellurine* 






855. 

Bisapomethylbrucine hydrochloride 





24 

856. 

Bisapomethylbrucine diacetate 





24 

857. 

Dimethylfurazane 

12 

bp760 

153° 

12 

24 

858. 

Dimethylfurazane oxide 

12 

bp27 

170-171° 

12 


859. 

Dicarbethoxyfurazane oxide 

12 

bp26 

173° 

12 

24 

860. 

Methyl N-( 5-tetrazalyl )carbamate 

49g 

mp 

>300° 

49g 


861. 

Product of thermal destruction of cyanogen 
chloride 





35 

862. 

Veratrine 

Commercial 




24 

863. 

Ricin* 

See Chap. 12 




See Chap. 12 

864. 

Ficin 





24 

865. 

Lubricating oil, S.A.E. No. 10 





24 

866. 

Fog oil, SGF No. 1 





24 


SECRET 


PART II 


SPECIAL PHYSIOLOGICAL AND TOXICOLOGICAL STUDIES 


SECRET 




THE ASSESSMENT OF PARTICULATES AS CHEMICAL 
WARFARE AGENTS 

By William L. Doyle and R. Keith Cannan 


15.1 INTRODUCTION 

D uring the years 1941-1945, more than 1,500 
compounds were examined in the United States 
as potential chemical warfare agents. The volatilities 
of the majority were so low that they could have 
little offensive value if used in the form of vapors.®-^^ 
On the other hand, a few were intrinsically so much 
more toxic or more vesicant than were the standard 
chemical warfare agents question of 

dispersing them in particulate form commanded con- 
sideration. Ricin (W), for example, was several score 
times as toxic as phosgene, whereas l,2-5fs(/?-chloro- 
ethylthio)ethane (Q), when applied in a solvent to 
the skin, was vesicant at one-tenth of the minimal 
blistering dose of mustard (H). 

Apart from observations incidental to the study of 
the screening power of smokes, little attention was 
paid to the toxicological properties of particulate dis- 
persions until the decision was made to submit finely 
powdered ricin to field tests. As a result of this de- 
cision, an expanding program of work was under- 
taken on the physical and toxicological assessment of 
dispersions of this material. As a result of the experi- 
ence gained, the investigations were later extended to 
a study of the vesicant effects of aerosols of 6fs(j8-chlo- 
roethylthioethyl) ether (T), Q, and ^m(/3-chloro- 
ethyl)amine (HNS). 

The point of departure of all the work was an ap- 
preciation of the paramount importance of particle 
size in determining the effectiveness of a particulate 
cloud (see Table 1). In the first place, the particle 
size determines the stability of the cloud under given 
meteorological conditions. Secondly, it controls the 
fraction of the area dose which will impact upon an 
obstacle in the path of the cloud, and therefore de- 
termines the hazard to the unprotected skin and 
eyes of an individual in the cloud. Finally, the im- 
pacting characteristics of the particles also control 
the inhalation toxicity of the cloud, since they affect 
the fraction of the inhaled material that will pene- 
trate to and be retained in the lungs. 

The problem of the assessment of particle size in 
fine liquid particulates had been greatly advanced by 


Table 1. Relation of particle diameter to chemical 
warfare characteristics. 


Particle 

diameter 

(microns) 

Type of cloud 

Characteristics of clouds 

10-3 - 10-2 

Vapor 

(molecular) 

Airborne, nonpersistent, sub- 
ject to laws of diffusion. 
Invades lungs, eyes, cloth- 
ing, and skin. 

10-1 

Aerosol 

Airborne and nonpersistent. 
Invades lungs. Does not 
impact out of streamlines. 

1 to 5 

Fine particu- 
lates 

As for aerosol except that it 
is more readily filtered and 
the lung retention is more 
complete. Five /j. is close 
to upper limit of nasal 
penetration. 

20 to 100 

Particulates 

Cloud persists in mild lapse 
conditions. Does not reach 
lungs. Impacts on surfaces 
and should invade eyes 
and skin. 

200 

Sprays 

Sediment rapidly. Impact 
efficiently. Not dealt with 
in this chapter. 


the British in the invention of the cascade impactor.^^ 
The attempt was made to adapt this instrument to 
the assessment of clouds of solid particles. However, 
the irregular size, shape, and density of the particles 
raised a number of difficulties which have not yet 
been satisfactorily resolved. Much fundamental 
work has, however, been carried out on the calibra- 
tion and use of the cascade impactor with dusts. 

The relation of particle size to the inhalation 
toxicity of toxic particulates was investigated by 
direct assays in animals of various species. Ricin 
aerosols of controlled ranges of particle size were 
utilized. At the same time the filtering character- 
istics of the human nose were measured by observa- 
tions of the extent of penetration of a variety of 
nontoxic particulates. The effectiveness of dis- 
persions of nonvolatile and of slightly volatile vesi- 
cants on human skin and on the eyes of animals were 
investigated as a function of particle size, wind 
speed, etc.^^*^ 


SECRET 


267 


268 


ASSESSMENT OF PARTICULATES AS CHEMICAL WARFARE AGENTS 


The results obtained in this work have shown 
clearly that the significance of the size of the air- 
borne particles cannot be reduced to any simple 
formula. However, the following broad conclusions 
would appear to be justified and may serve to indi- 
cate the status of the problem. 

1. The size, shape, and density of the particles, as 
well as the wind speed and other meteorological con- 
ditions, all contribute to the aerial behavior of a 
particulate cloud. Particles with effective diameters 
greater than about 100 sediment rapidly in a stable 
atmosphere. They will remain airborne for significant 
periods only under conditions of considerable turbu- 
lence. On the other hand, clouds containing effective 
concentrations of particles smaller than 0.1 ^ in di- 
ameter are subject to rapid aggregation. For example, 
if a cloud with a concentration of 1 mg/1 were com- 
posed initially of very small particles, it would attain 
relative size stability only when the average particle 
diameter had grown to about 0.7 m- 

These considerations lead to the conclusion that 
the problem of toxicological effectiveness may be 
restricted to a consideration of clouds whose parti- 
cles (if of unit density) fall within the size range of 

0.1 to 100 M. 

2. In general, toxic agents are much more effective 
if they enter the lungs than if they are retained in the 
nose. The probability that a particle will penetrate 
the nasal barrier increases as the size of the particle 
diminishes. Available evidence indicates that the 
optimum size for penetration to and retention in 
human lungs probably lies within the limits of 
0.5-3 n in diameter. The optimum size for labora- 
tory animals is appreciably lower. These values are 
for resting animals and are further lowered at the 
high ventilation rates associated with exercise. 

3. The probability of the impaction of a particle 
on a surface in the path of a cloud increases with the 
size of the particle. At moderate wind speeds, the 
fraction of the area dose which may be expected to 
impinge on the surface becomes significant if the 
particle size is above 10 m and becomes an important 
fraction of the area dose above a size of about 70 

It would appear from items 2 and 3 that no single 
dispersion can exploit to the full the potentialities of 
an agent which, like Q, is both vesicant by contact 
and toxic by inhalation. This is a fundamental di- 
lemma which imposes serious limitations on the 
offensive potentialities of aerosols of this type. 

4. If munitions were available which would dis- 
perse particulate material in either of the optimum 


size ranges indicated above, new orders of inhalation 
and of vesicant effectiveness in the field should be 
obtainable. Such munitions have not yet been ade- 
quately developed.^® 

15.2 TYPES OF PARTICULATES 

15.2.1 Sternutators 

Classical sternutators such as diphenylamine- 
chlorarsine (adamsite), diphenylaminecyanoarsine 
(cyan DA), and toxic sternutators such as aconitine 
and nitrophenyldichlorarsine are primarily harassing 
agents. These agents act at concentration time prod- 
ucts (C^’s) considerably below 0.1 mg min/m^ At 
present there is little interest in these agents because 
they are stopped by available masks and because 
trained troops carry on effectively despite their pres- 
ence. It is possible, however, that the utility of 
sternutators has not been adequately considered. 
Larger particles than those that have been utilized 
may be more harassing. German interest in mixtures 
of sternutators with mustard may indicate at- 
tempts to hide the presence of more toxic agents. 

15.2.2 Toxic Particulates 

1. Inorganic substances, e.g., cadmium selenium. 

2. Synthetic organic compounds, e.g., aromatic 
carbamates. 

3. Naturally occurring substances, e.g., ricin (W). 

The metals are thermally stable and may be in- 
corporated in standard smoke incendiary or high- 
explosive weapons. As indicated in Chapter 11, these 
substances are not more toxic than standard chem- 
ical warfare agents, but they may be used without 
ready detection in various types of munitions. 

Although the aromatic carbamates are consider- 
ably more toxic than standard agents,^® they are un- 
stable in aqueous solution and to heat. For these 
reasons, little serious consideration has been given 
to their use as particulate clouds. 

Ricin (W) is intrinsically somewhat more toxic 
than the best of the carbamates. It is also thermo- 
labile. Its toxicity when dispersed as a cloud has been 
studied extensively in the laboratory and prelim- 
inary field trials, using special munitions, have been 
carried out. This interest in ricin was not entirely 
dependent on its own merits as a toxic agent. It was 
recognized as a prototype of toxic protein materials 
of bacterial origin which were known to have even 
greater toxicity but which were less conveniently 
prepared and handled. 


SECRET 


EFFECTIVENESS OF PARTICULATE CLOUDS 


269 


15.2.3 Vesicants 

1. Volatile vesicants, e.g., mustard (H), tris(^- 
chloroe thy 1) amine (HNS). 

2. Nonvolatile vesicants, e.g.,^’^ 6zs(i8-chloroethyl- 
thio)ethane (Q). 

All the members of this group are toxic, but not so 
toxic as those in Section 15.2.2, (1) and (2). They 
are, however, vesicant. The best nonvolatile vesi- 
cants are intrinsically more toxic and more vesicant 
than the volatile ones. Q is inherently 10 to 20 times 
as vesicant as H and at least 5 times as toxic.^’®’^^®’^®^ 
They should be more difficult to detect than the 
volatile agents. In the field they will not be expected 
to create a vapor hazard, but, by contamination of 
equipment, should establish a contact hazard for 
bare skin which it would be difficult to eliminate by 
decontamination. It is doubtful if nonvolatile vesi- 
cants can be effective through clothing. 
volatile members of this group can be dispersed 
thermally, by means of airplane spray, or by high 
explosive-chemical shells. The particle size achieved 
will markedly influence the action of the agent. Thus, 
very small particles ( 0 . 2 - 1.0 n in diameter) may be 
nonvesicant because of streamlining, but will be 
more toxic by inhalation and will also yield the great- 
est and most rapid vapor return. Larger particles 
(5 to 25 fx) will have greater vesicancy, but probably 
at the expense of toxicity. The largest particles (200- 
2,000 m ) may be most effective for the penetration of 
clothing, particularly of the permeable protective 
type. The largest particles may also create a contact 
and traversal hazard. 

These statements are broad and tentative general- 
izations based upon contemporary views of the char- 
acteristic behavior of particles of different diameter. 
Many of these generalizations require further experi- 
mental investigation. The results of contemporary 
work are reviewed in Section 15.5.1. 

15.3 THE EFFECTIVENESS OF PAR- 

TICULATE CLOUDS 

15.3.1 Stability 

Sedimentation. The rate of sedimentation of 
particles in a static atmosphere increases with in- 
crease in particle size. Computations based upon 
kinetic considerations indicate that precipitation be- 
comes rather rapid when the effective diameters of 
the particles exceed about 100 m- Clouds of such large 
particles could be maintained in the air for significant 


periods only under strongly turbulent conditions. 
They are sprays rather than clouds and find their 
natural use for contact and ground contamination 
— e.g., as airplane sprays. The optimum particle size 
for such sprays depends on a variety of factors — 
the speed of the plane, the turbulence, the vola- 
tility of the agent, etc. — ■ which it is not the 
province of this chapter to discuss.^® Suffice it to 
say that for direct assault upon exposed personnel 
there is general agreement that the optimum range 
of particle size to obtain massive and diffuse con- 
tamination with a vesicant is about 0.3-2 mm in 
diameter. If ground contamination is the objective, 
the upper limit of size may be unimportant. 

Coagulation. Although the rate of sedimentation 
sets the upper limit of size in a persistent aerosol, the 
tendency of particles to coalesce upon collision estab- 
lishes a lower limit of particle size stability. On simple 
considerations of collision frequency, the half life of 
a particle should be roughly proportional to the con- 
centration of the aerosol. With increase in particle 
size, the concentration required to give a fixed half 
life increases with the mass, and therefore with the 
cube of the radius of the particles. It has been esti- 
mated that the half life of an aerosol containing 
5 X 10® particles per milliliter is 6 minutes at room 
temperature. For particles of 0.1 /z in diameter and 
unit density, this corresponds with a concentration 
of 2.5 /zg/1. For particles of 1 /z in diameter, the cor- 
responding concentration is 2.5 /zg/1. If these clouds 
were initially established in higher concentrations, 
they would aggregate until the numbers of particles 
in unit volume had fallen to a relatively stable level. 
It should be noted that the tendency to coagulate 
does not lead directly to a reduction in mass concen- 
tration, but rather to an increase in average particle 
size. The phenomenon is important, therefore, only 
if clouds of small particle size are required. There is 
no purpose in attempting to disperse a particulate in 
a smaller particle size than can be sustained by the 
concentration that is to be established. If a concen- 
tration of 1 /zg/1 is accepted as the lowest which the 
toxicity of the material would justify, then the small- 
est particle size which it is worth while attempting to 
disperse is of the order of 1.0 /z. 

In summary, therefore, considerations of rates of 
sedimentation and of coagulation suggest that we 
should concern ourselves with the behavior of air- 
borne particles in the size range of 0.1-100 /z in diam- 
eter, corresponding to a 10^-fold range of particle 
mass. 


SECRET 


270 


ASSESSMENT OF PARTICULATES AS CHEMICAL WARFARE AGENTS 


15.3.2 The Significance of Particle Size 

The tactical use of a chemical warfare agent in the 
form of a cloud is, in general, to be justified only 
when the conditions of the operation will be such 
that personnel exposed to the cloud will absorb 
casualty-producing doses through the lungs or 
through the skin. When the cloud is a true vapor, 
the actual dose that is inhaled under standard con- 
ditions of respiration can be predicted from the prod- 
uct of the concentration and the time of exposure 
{Ct). The amount of vapor absorbed from the skin 
under standard conditions of temperature and hu- 
midity can, likewise, be predicted from the Ct, since 
the rate of diffusion of the vapor to, and the rate of 
penetration of, the skin may generally be taken to be 
proportional to the concentration. It follows that an 
effective dosage on the target can be assured if muni- 
tions expenditure is properly adjusted to the meteor- 
ological conditions. 

The tactical requirements cannot be formulated so 
simply when the cloud is composed of particles with 
colloidal or larger dimensions. In this situation, the 
concentration of the agent may actually be less im- 
portant than the sizes of the airborne particles. It 
has been noted that this is a factor in determining 
the stability of a particulate cloud. In the case of an 
agent which is toxic by inhalation the particle size 
also controls the proportion of the inhaled material 
which is filtered out of the inspired air in the respira- 
tory passages. Likewise, in the case of a vesicant, the 
amount of material deposited upon an exposed sur- 
face at a given Ct and wind speed is a function of the 
particle size. In brief, the effective dose of an inhalant 
and of a vesicant depends on the impinging char- 
acteristics of the particles which, in turn, depend 
upon the size and density of the particles. 

15.3.3 The Impingement of Particles 

The amount of an airborne particulate which will 
deposit on an object in the path of a cloud will be the 
sum of the amount which impinges upon the object 
and the amount which is deposited under gravity.'^® 
Since this discussion has been limited to clouds in 
which the rate of sedimentation is small, considera- 
tion may be confined to the amount which impinges 
on the object. 

The probability that a spherical particle will im- 
pinge upon a cylindrical surface in its path is given 

by 


p = a (1 _ 

In this equation, u is the velocity of the particle, d its 
diameter, and p its density. D is the diameter of the 
target, while a and a are constants. It will be seen 
that the tendency to impinge increases with the size 
and with the density of the particle and also with the 
wind speed. It depends also on the size and shape of 
the target. According to Sell,^® when d, a — 
0.75 and a = 650 cgs units. More recent experi- 
mental data give values of a = 0.75 to 1 and a = 
70 cgs units. 

It may be assumed that all liquid particles which 
impinge upon a surface will remain adherent to it, 
but it is not expected that this will be true for a solid 
particulate. In this case the probability of adherence 
to the surface may be much lower than the probabil- 
ity of impingement. The magnitude of the losses will 
depend upon the nature of the surfaces of the target 
and of the particulate. 

15.3.4 The Effective Vesicant Dose 

The toxicologically effective dose of a nonvolatile 
vesicant may be taken to be proportional to the 
amount of the agent which is deposited on unit area 
of a surface exposed to the cloud in question. This 
amount is given by the product of Ct, u, and /, where 
u is the wind speed and / is an impaction factor. The 
latter corresponds with the fraction of the area dose 
which is deposited on the target. When the cloud is 
homogeneous with respect to size and density and 
the adhesiveness of the surface for the particles is 
high,/ is given by P in equation (1). When the cloud 
is heterogeneous, it is necessary, in principle, to 
measure the distribution of the total concentration 
over the particle sizes which are present and to de- 
rive an overall impaction factor for the cloud. 

P is an exponential function of the size of the parti- 
cle. When its value is considerably less than unity, it 
increases rapidly with small increases in particle size. 
For this reason, the impacted dose of a heterogene- 
ous cloud may be largely determined by the rela- 
tively small number of the larger particles which are 
present. A heterogeneous cloud may, therefore, be a 
much more effective vesicant than a homogeneous 
cloud having the same mass median diameter. 

Further complications are introduced if, as may 
occur with solid particulates, the particles vary in 
shape and density as well as in volume. A very im- 
portant example of such variations is the formation 


SECRET 


PRODUCTION AND CONTROL OF PARTICULATE CLOUDS 


271 


of loose irregular aggregates of low density from 
smaller primary particles of uniform density. This 
type of aggregation is prone to occur during the dis- 
persion of powdered materials, particularly if they 
are somewhat hygroscopic. The effects of these com- 
plicating factors on the impingement of solid parti- 
cles are elaborated in Section 15.4.3. 

When one is dealing with a particulate cloud of a 
slightly volatile agent such as HNS, consideration 
must be given to the toxic effectiveness of the vapor 
as well as to that of the dispersed phase. It must be 
remembered, also, that the characteristics of the 
cloud continually change with time. The particulate 
phase suffers progressive loss in concentration and 
size as volatilization proceeds until a pure vapor 
cloud results. An analysis has been made of the fac- 
tors which determine the rate of evaporation of air- 
borne particles.®^ 

It is of interest to note that the wind speed has two 
opposed effects on the tactical efficiency of a vesicant 
particulate cloud. The greater the velocity of the 
wind, the lower is the concentration of an agent 
which is being generated at a fixed rate. On the other 
hand, the greater the wind speed, the greater is the 
impaction efficiency of a given concentration of the 
particles. 

Experimental studies of the relation of particle 
size to the vesicancy of aerosols of Q, T, and HNS 
are reviewed in Section 15.5.1. 

15.3.5 Effective Inhaled Dose 

It is generally acknowledged that toxic particles 
are less effectively absorbed from the nasal and 
respiratory passages than from the alveoli of the 
lungs. Considering the pulmonary toxicity alone, the 
effective dose of an inhalant may be given as the 
product of Ct, V, and (1-/) where v is the minute vol- 
ume of respiration, and / is the fraction of the inhaled 
material which is trapped in the respiratory passages. 
It will be agreed that this fraction is determined in 
large measure by the amount of impaction in the 
nose. It may be expected to vary with the species of 
animal, and, to some extent, from animal to animal 
of the same species. It will also vary with the physi- 
ological state of a single animal. To the extent that 
impingement in the nose determines /, an increase in 
rate of respiration will, by increasing the velocity of 
the particles in the nasal passages, result in a greater 
nasal retention and a reduced effective dose. 

The question of the extent to which particulate 
material which enters the alveoli is retained and ab- 


sorbed has been investigated in a preliminary way. 
The results are summarized in Section 15.5.2. 

Experimental studies of the effects of particle size 
on the toxicity of ricin for animals and on the reten- 
tion of nontoxic particulates in the human nose are 
reviewed in Section 15.5 and in Chapter 12. 

15.4 LABORATORY PRODUCTION AND 
CONTROL OF PARTICULATE CLOUDS 

15.4.1 Dispersal 

Liquids and Solutions. In a few special studies the 
Sinclair-LaMer homogeneous smoke generator has 
been used.^-^ Thermogenerators may be employed 
for the dispersal of stable, slightly volatile agents. 
In most cases, however, various types of atomizer 
have been used under conditions of operation which 
have been empirically determined to give clouds of 
the desired characteristics. Preliminary studies of 
the fundamental properties of atomizers have been 
reported. 

A useful method of producing clouds of varying 
particle size from a standard atomizer has been the 
following. A nonvolatile cosolvent is mixed in vary- 
ing proportions with a dilute solution of the agent in 
a volatile solvent. When these mixtures are atom- 
ized, the mass median diameters of the particles in 
the cloud vary with the proportion of nonvolatile 
solvent in the original mixture. For example, glycerol 
has been found to be a satisfactory cosolvent for 
aqueous solutions of ricin and dibutyl phthalate for 
solutions of nonvolatile vesicants. 

Solids. Electric arcs employing the toxic agent as 
one component of the electrodes provide useful 
sources of finely divided metals and their oxides. 
Thermal generation of toxic clouds by the incorpora- 
tion of the agent in incendiary or fuel block mixes 
may also be used when the agent is thermostable. 
Such thermal generators tend, however, to give dis- 
persions which coagulate rapidly.^^-^®-^^ 

The obvious alternatives in the case of a thermo- 
labile solid such as ricin are to disperse by atomiza- 
tion of a solution or to generate a dust cloud from a 
finely comminuted powder. Most devices which have 
been described for the dispersal of powders lead to a 
fractionation of the sample. In some it is the smaller 
particles, in others, the larger particles which tend to 
disperse the more rapidly. In most there occurs a 
considerable formation of loose aggregates in the 
cloud. Although some attempts have been fairly suc- 
cessful,^^*"’^^^ no really satisfactory method for the 


SECRET 


272 


ASSESSMENT OF PARTICULATES AS CHEMICAL WARFARE AGENTS 


uniform dispersal of a powder at a rate of a few milli- 
grams a minute has been described. The devices 
which lead to least aggregation in the cloud have the 
disadvantage of a variable rate of delivery. (See 
Section 15.6 for dispersal in the field.) 

15.4.2 Measurement of Size 

The assessment of particle size in a cloud requires 
not only the observation of the range of sizes in the 
cloud, but also the amounts of material in the differ- 
ent size categories. The results are comprehensively 
expressed as curves in which the cumulative amount 
of material is shown as a function of the diameter of 
the particle. Three types of curves may be distin- 
guished, according to whether the particle diameter 
is plotted against (1) the number, (2) the volume, or 
(3) the mass of airborne particles. From these curves 
may be derived respectively a number median di- 
ameter [NMD], a volume median diameter [VMD], 
and a mass median diameter [MMD]. The number 
distribution is appropriate if one is interested in ef- 
fects dependent on the number rather than on the 
mass of airborne particles — as, for example, in the 
knockdown of mosquitoes. The volume distribution 
has no particular practical significance, but is the 
form in which results must be cast if the densities of 
the particles are not known and the amount of ma- 
terial must be evaluated from microscopic observa- 
tions of the numbers and diameters of the particles 
in the sample. The mass distribution is the descrip- 
tion of particle size which is most significant to the 
problem of the vesicant and toxic effects of the cloud. 

The clouds from atomized liquids have fairly typi- 
cal distributions and the densities of the particles are 
uniform. In such conditions the MMD is sufficient 
to characterize the cloud satisfactorily. In dust 
clouds generated from powders, on the other hand, 
the distribution of sizes may be quite abnormal, the 
unitary particles may be far from spherical, and 
many aggregates of low density may be present. The 
MMD of such a cloud may be a quite misleading in- 
dex of the impaction efficiency of the cloud. The 
complete mass distribution is required for the char- 
acterization of such a cloud. 

Methods. When dealing with dusts it is desirable 
to make counts of the undispersed material for com- 
parison with the airborne cloud. The MMD and the 
range of sizes in a given preparation are best deter- 
mined by direct microscopic examination if the MMD 
is below 10 The work is tedious and various meth- 
ods have been discussed to save labor but critical in- 


vestigators agree with Fairs on the procedure to be 
followed. Hard and fast rules for the number of parti- 
cles to be counted cannot be stated. The statistical 
features of the problem are well presented by Dalla- 
valle.^^ The suitability of a laboratory or field proce- 
dure for the measurement of the particle size in a 
cloud depends upon the size of the particles, whether 
they are liquid or solid, upon the time available for 
sampling, and upon the concentration. Optical meth- 
ods suited to the analysis of homogeneous smokes 
have been developed. ^ These methods are not readily 
applicable to heterogeneous clouds, but some at- 
tempts in this direction have been made.^® In general, 
the optical methods result in neglect of the relatively 
small numbers of coarse particles which may carry 
an appreciable fraction of the mass. An instrument 
capable of photoelectric measurement of the surface 
area of individual particles is not theoretically impos- 
sible. In view of the labor required in available pro- 
cedures, some such device is highly desirable. 

Ultra microscopic and dark field observations of 
falling particles have frequently been employed.'^* 
Such methods are limited to- particles small enough 
to remain airborne prior to observation and to con- 
centrations so low that coagulation is avoided. There 
is great danger that large particles will be lost in the 
sampling procedures prior to observation. 

The thermal precipitator is very useful for parti- 
cles below 5 to 10 M in diameter, provided that the 
cloud is available for a sufficient period of time so 
that the necessarily slow sampling rate provides an 
adequate sample. 

For clouds ranging from 2.0 to 50 /x in diameter, 
there is one instrument at present which avoids many 
of the difficulties inherent in other methods. This is 
the cascade impactor.^®-^^ It merits more detailed 
consideration than those already referred to. 

15.4.3 The Cascade Impactor 

This instrument consists of a series of four jets ar- 
ranged in series so that the sampled cloud impinges 
at four increasing velocities on to suitably prepared 
microscope slides (A,B,C, and D). In this way the 
particles are separated into four impacted groups. 
The size ranges trapped on successive slides overlap 
to some extent, but the MMD*^ of the material on a 

® The British workers employed the effective drop size 
[EDS] in place of the MMD to characterize the slides. The 
EDS is approximately the size below which 98 per cent of the 
number of particles on each slide is found and for most clouds 
is about 1.5 times the diameter of the mass median. 


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PRODUCTION AND CONTROL OF PARTICULATE CLOUDS 


273 


particular slide is, under favorable conditions, char- 
acteristic of that slide. Under such conditions, there- 
fore, it is necessary only to measure the amount of 
material on each slide in order to obtain a rather 
satisfactory assessment of the mass distribution. 
The amount of material on a slide may be computed 
from microscopic counts or by chemical analysis. 

The cascade impactor has a number of obvious ad- 
vantages over single jet instruments such as koni- 
ometers, the Owen’s jet, etc. It was originally de- 
vised and calibrated for the assessment of 

liquid particulates. For nonvolatile liquids quite pre- 
cise data can be obtained if proper consideration is 
given to the following variables. 

In the first place the MMD of the material im- 
pacted on any one slide depends to some extent on 
the MMD of the cloud as a whole. It depends also on 
the shape of the distribution curve of the cloud. 
Values of the MMD’s on the four slides have been 
determined experimentally for clouds of MMD 5, 
10, 16, and 100 Impingement of a particle on a 
given slide is a question of statistical probability. 
The particles of a homogeneous cloud are distributed 
over more than one slide. Calculations have been 
made of the mass distribution on the slides which 
should be obtained with strictly homogeneous 
clouds.^®™ Secondly, the MMD of the particles 
on a slide depends on the velocity of operation of the 
impactor. Experimental results indicate that the 
MMD is proportional to the reciprocal of the square 
root of the flow rate. 

As the result of the analysis of the counts of a 
large number of slides a characteristic mass distri- 
bution curve has been constructed.^®^ By means of 
this curve it is possible, by chemical analysis of the 
amounts of material on the slides in a given experi- 
ment, to arrive at a fair estimate of the MMD’s on 
the four slides. When an instrument has been cali- 
brated in this way, the use of chemical methods of 
analysis eliminates the very tedious process of micro- 
scopic assessment of the slides. 

Dust Clouds. The use of the cascade impactor for 
the assessment of clouds of solid particles was first 
investigated in this country. It will be evident 
from what has already been said that its use for this 
purpose is complicated by a number of factors which 
arise from the diversity of the characteristics of solid 
particles. Solid particles may be highly irregular in 
both shape and density. It has been found, for ex- 
ample, that samples of ricin prepared by the spray 
drying of aqueous solutions consisted largely of hol- 


low spheres. When this material was further de- 
graded by air grinding the product was chiefly in the 
form of thin disks. Again, the particle size distribu- 
tions in dusts may be quite different from those char- 
acteristic of atomized sprays. The spray-dried ma- 
terial referred to was remarkably uniform in size, 
whereas ball-milled preparations of ricin contained a 
wide range of particle sizes with a large number of 
extreme fines. Finally, the adhesion of impinging 
solid particles may be incomplete and the degree of 
slippage may change progressively as the slide be- 
comes coated with the agent. 

These factors combine to give a wider distribution 
of particle sizes on a single slide than is obtained 
when an atomized liquid is assessed. When the parti- 
cles are not spherical, the problem arises of the 
proper method of computing their volumes from 
observations of their dimensions under the micro- 
scope. Serious errors may arise if they are treated as 
if they were spheres. The volume of a sphere is 
0.524d®. Heywood has listed some of the factors by 
which the cube of the observed ‘Miameter” should be 
multiplied when the particles depart from the spheri- 
cal. The factor for a rounded particle is given as 0.54, 
for a prismoidal object it is 0.47, and for a tetra- 
hedral particle it is 0.38. A mean value of 0.5 is sug- 
gested for a heterogeneous assembly of nonspherical 
particles. 

Recent work has confirmed the validity of this 
factor for slides C and D, but it has not always been 
possible to apply it to slides A and B because it is on 
these slides that the large highly irregular and often 
disk-like particles are found. To measure the mean 
lateral dimensions of such particles and compute 
their volume as though they were spheres leads to an 
MMD for the slide which is much greater than the 
true value. Some attempt should be made to measure 
the thickness of plate-like objects and to calculate 
their rectangular volumes. 

The frequent occurrence of aggregates in a solid 
particulate has proved to be particularly trouble- 
some.®^ The MMD of the particles impacted on a 
particular slide varies with the square root of the 
density. Since the density of a loose aggregate may 
be less than one-tenth of that of the unitary particles 
of which it is composed, it is evident that the presence 
of many aggregates on a slide may profoundly change 
the MMD of that slide. The problem of the density 
to be assigned to an aggregate in order to compute 
its mass is also a difficult one. Microscopically the 
best that can be done is to take a few representative 


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274 


ASSESSMENT OF PARTICULATES AS CHEMICAL WARFARE AGENTS 


aggregates, count the number of unitary particles in 
them, and sum their volumes. The density may then 
be taken to be the ratio of this volume to the volume 
of the whole aggregate treated as a sphere. 

Many aggregates disintegrate when they impact 
on a slide. They will be assessed as though they corre- 
sponded in impinging properties with the unitary 
particles of which they were composed, although the 
latter would probably not have appeared on that 
slide had they not been aggregated. The result will 
be artificially to reduce the MMD below its real 
value. 

When unusually large particles are present in a 
cloud, losses may occur by impingement on the walls 
of the orifice of the instrument, particularly when 
the impactor is operated in a static cloud. Under 
conditions of isokinetic sampling of clouds moving 
with average wind velocities it has been calculated 
for liquid droplets that orifice losses become appar- 
ent with droplets about 50 n in diameter and in- 
crease as the size further increases. Similar calcula- 
tions for aggregates with a density of 0.1 indicate 
that the upper limit for reliable sampling is about 
160 M. The upper limits for static clouds are probably 
appreciably below these figures because of increased 
turbulence around the leading edge of the orifice. 

Summary. The emphasis which has been laid 
upon the evaluation of the sizes of particles on the 
impactor slides has tended to distract attention from 
the fact that the cascade impactor does not measure 
the size of a particle but rather its impingement tend- 
ency. Most of the difficulties in applying the instru- 
ment to the assessment of dusts have been in express- 
ing the distribution of impacted material in terms of 
volumes and masses computed from microscopic ob- 
servations of the dimensions of the particles. This 
has been a necessary preliminary to the calibration 
of more direct methods of interpreting the results 
obtained. In so far as the toxicity of particulate ma- 
terial is a function of the amount of material which 
will impact in the nose or on exposed surfaces the 
efficiency of a cloud should, most logically, be de- 
scribed in terms of its impaction factor under stand- 
ard conditions. The use of particle size to characterize 
the cloud is a convention which may, perhaps, be 
discarded when instruments which measure impinge- 
ment have been properly calibrated. 

The MMD of slide B of the cascade impactor is 
close to or slightly greater than the maximum size of 
particles which have been found to penetrate the 
nasal barrier in most animals. The fraction of air- 


borne material which collects on slides B, C, and D 
under standard conditions of operation should, there- 
fore, be somewhat greater than the effective inhala- 
tion dose. Calibration of the instrument in such a 
way as to establish a relation between these two 
fractions should make possible an estimation of the 
inhalation toxicity of a cloud from a chemical analy- 
sis of the impactor slides alone. 

The effective dose of a vesicant is dependent on 
the fraction of airborne material which is large 
enough to impact efficiently. Most of this fraction 
should be captured by slide A. The analysis of im- 
pactor slides operated in clouds of nonvolatile liquid 
vesicants should lead without much difficulty to 
satisfactory estimates of the effective vesicant dose. 

15.5 PARTICLE SIZE AND TOXICITY 

15.5.1 Vesicant Effects 

The dose of a particulate which is deposited on an 
object depends upon the amount settling out plus the 
amount impacting.^® The amount impacting will vary 
with the wind speed, density of the particle, area of 
the particle, diameter of the target, and nature of the 
surface of the target. A heterogeneous cloud of 
MMD 2.0 u may have the same impactibility for a 
given surface as a homogeneous cloud of MMD 4.0 /z. 

The impingement pattern on the object will vary 
with particle size from a diffuse pattern with vapors 
and smokes to a localized (upstream surface) mosaic 
with coarse sprays. The volatility of the agent and 
the rate of absorption of the material by the target 
will affect the physiologically effective dose. 

Preliminary indications of the order of magnitude 
of effect of particle size on vesicancy of a nitrogen 
mustard (HNS) and a nonvolatile vesicant (T) were 
obtained by exposures of forearms in a wind tun- 
nel. At 5 mph wind speed and under condi- 
tions of temperature (about 80 F), relative humidity, 
and skin resistance (sweating index) such that a 
vapor of HNS at a Ct of 1,200 mg min/m^ produces 
an erythema, the following tentative conclusions 
were reached. Smokes of MMD below 2.0 m are less 
effective than vapor. A heterogeneous (atomized) 
cloud of MMD 2.0 u was equally as effective as vapor. 
A heterogeneous cloud of MMD 8.0 fx was twice as 
effective but the erythema was more localized. HNS 
is less volatile than mustard. T is practically non- 
volatile. The relation of volatility and particle size 
to vesicancy is illustrated by the following relation- 
ships. By topical application of single drops to fore- 


SECRET 


PARTICLE SIZE AND TOXICITY 


275 


arms it takes 10 times as much HNS to produce the 
same skin reactions as a given amount of 
As a 2.0 -m (heterogeneous) particulate, a of 45 
of T (area dose = Ct X 5 mph) is the equivalent of 
a Ct of 1,200 mg min/ m^ of HNS ; T is thus 27 times as 
vesicant as HNS. When the particle size is raised to 
8.0 fjL, a Ct of 6 to 10 of T is as effective as a Ct of 600 
of HNS, thus demonstrating a factor of 100 or more 
in the vesicancy of these agents.^®^ These findings 
demonstrate the importance of designing munitions 
which will disperse the chosen particulate in an opti- 
mum size range. 

Owing to the great effect of temperature and 
humidity on skin reactions to given exposures, 
it is difficult to generalize from these data to other 
agents and conditions. By employing the appropriate 
factors for comparison of vesicant power, com- 
parisons may be made with the values given in 
Chapters 5 and 6. Under the conditions obtained in 
the experiments described in the preceding para- 
graphs, H vapor is about one-half as effective as 
HNS vapor. The effect of evaporation of the agent 
after deposition on the skin has been found to be 
approximately the same for H and HN3,^®®’^ despite 
differences in volatility. It will be indicated in the 
next section that of a heterogeneous cloud of T of 
MMD 8.0 fi, only 10-15 per cent will penetrate the 
human nose. 

The results on vesicancy in relation to particle 
size apply to exposed skin areas. The presence of 
clothing profoundly modifies the situation. A droplet 
of nonvolatile agent on the surface of clothing can 
under some circumstances be considered innocuous, 
whereas a volatile agent will generate vapor which 
may be drawn over the underlying skin by the bel- 
lows effect of clothing. Numerous tests have been 
carried out on the droplet diameter required to pene- 
trate clothing by wetting the cloth. The sizes in- 
volved are well above the particulate range consid- 
ered here. Relatively few data on the penetration of 
clothing by small particles are available for chemical 
warfare agents. The amount of a particulate found 
on clothing is a function of filtration and impaction. 
A given expenditure of agent will with increasing 
wind speed deposit decreasing amounts on (and 
through) the cloth by filtration (bellows effect) but 
will deposit increasing amounts by impaction, espe- 
cially for coarser particulates. For nonvolatile sub- 
stances the amount penetrating cloth by impaction 
forces appears to be a small fraction of the amount 
penetrating by filtration. 


For nonvolatile materials there is definite disad- 
vantage to the use of particulate clouds coarser than 
1 to 2 in diameter if penetration of clothing is to be 
achieved. Increased turbulence at higher wind speeds 
appears to reduce the percentage that penetrates by 
filtration. 

15.5.2 Penetration of the Nose 
Initial experiments were designed to determine the 
particle diameter at which 50 per cent of the mass of 
a given cloud passes the nose.^^‘^'2®-29 Values obtained 
on four human subjects are given in Table 2. 


Table 2. Penetration of the human nose by particulates. 


Agent 

Density 

(g/ml) 

Flow rate 
(1pm) 

Diameter for 
50 per cent 
penetration 
( m ) 

Corn oil 

0.93 

17 

5.6 



60 

1.8 

Dry NaHCOs 

2 . 2 * 

17 

2.1 



60 

0.8 


* Actual density in nose somewhat lower because of hydration of par- 
ticles. 


These experiments were extended in an attempt to 
determine the percentage penetration of the nose at 
various sizes for materials of differing physical char- 
acteristics, e.g., liquid corn oil of density 0.9 and dry 
NaHCOs of density 2.0, and at various rates of 
breathing. The results are presented in Figures 1 
and 2. It is of interest that there is little difference in 



ai 1.0 to 

MASS MEDIAN DIAMETER IN MICRONS 

Figure 1. Nasal retention of particulates in man. 


nasal penetration between flow rates of 17 and 29 1pm 
(unpublished data). A change from 17 1pm to 60 1pm 
changes the value for 50 per cent penetration from 
2.1 to 0.8 Regardless of flow rate or density, parti- 


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276 


ASSESSMENT OF PARTICULATES AS CHEMICAL WARFARE AGENTS 


cles 10 /i in diameter have approximately a 10 per 
cent chance of penetrating the nose. 

Over the size range shown in Figures 1 and 2 it 
would appear that for a given particle diameter the 



0.1 1.0 10 


MASS MEDIAN DIAMETER IN MICRONS 
Figure 2. Lung retention of particulates in man. 

lung retention is about 20 per cent more efficient 
than the nose. From another viewpoint, the same 
efficiency in retention obtains for particles in the 
nose which are 2.5 times the diameter of those in the 
lung. 

When molecular dimensions are reached the nasal 
and lung retentions increase above those found at 
0.2 

15.5.3 Inhalation Toxicity in Animals 

Mice, rats, and rabbits were exposed, while at rest, 
to particulate clouds of W in glycerol at controlled 
HMD’s. The relation between particle size and 
L(C05 o is shown in Figure 3. For the size range 0.5 to 
7.0 M the effect is much more pronounced in rats and 
mice than in rabbits. These data, which are reviewed 
in more detail in Chapter 12, should be compared 
with those of British authors using other tech- 
niques. 

15.6 DISPERSIBILITY OF PARTICULATES 

In the laboratory it is relatively simple to prepare 
clouds of unitary particles by atomization, thermal 
generation, or in electric arcs. Previously comminu- 
ted powders may also be dispersed largely as unitary 
particles in special apparatus. Munitions capable of 
dispersing previously comminuted powders in the 
unitary state have yet to be developed. Powders 
differ in ease of dispersibility, as shown in various 



Figure 3. Inhalation toxicity of ricin in relation to 
particle size. 


laboratory tests. Such tests are, however, generally 
meaningless in terms of dispersibility by field muni- 
tions. The factors involved in field munitions which 
are difficult to scale up from laboratory tests include 
aggregation phenomena occurring prior to, at the 
time of, and immediately subsequent to dispersal. 
These aggregation phenomena are influenced by ge- 
ometry, strength of materials, brisance of explosives, 
and scale of munition. 21-22 

To date field experiments have, however, almost 
universally confirmed the finding that suspensions 
in organic nonsolvent media result in much higher 
dispersion efficiencies than can be obtained by use of 
gas ejection munitions or standard munitions with 
dry fillings. Owing to low bulk density of dry fillings, 
suspensions permit a higher ratio of active filling to 
munition weight. 

15.7 FIELD ASPECTS OF PARTICULATE 
ASSESSMENT 

The outstanding observation resulting from field 
experiments on dispersion of previously comminuted 
powders by field munitions is the fact that the frac- 
tion of material airborne in the size range of the 
original filling is generally insignificant. Most of the 
mass of the filling appears in a highly aggregated 


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FIELD ASPECTS OF PARTICULATE ASSESSMENT 


277 


state. Field sampling must not only evaluate the 
gross clumping and spillage but also account for the 
low toxicity (in terms of chemical Ct or area dose) of 
the more lastingly airborne clouds. The frequently 
occurring light fluffy (snowflake) aggregates are gen- 
erally not encountered in laboratory investigations. 
They are particularly deceptive since they may be 
readily disrupted in the sample and thus appear as a 
group of component unitary particles. 

The orifice velocity of field sampling equipment 
should not deviate markedly from the wind speed if 
particles above 50 ju in diameter are to be readily 
sampled. Where power-operated devices are em- 
ployed, the requirements of pump capacity for ap- 
propriate sampling of particulates, which are higher 
than for vapors, may cause some embarrassment. 

In early experiments fine wires were tested as 
sampling devices but discarded because of the differ- 
ing impaction efficiencies for small and large parti- 
cles.^^ By employing wires or tubes of three different 
diameters, however, the relation of collection effi- 
ciency to wire diameter can be utilized to calculate 
particle size and area dose from the mass of material 
collected on each size of This device 

dispenses with power requirements when sampling 
in wind speeds above 3 mph. At 1 mph corrections 
for settling are required. 


There are marked difficulties in the assessment of 
initial clouds containing vapor and particulate con- 
centrations. The chemical drop trap and the chem- 
ical selector indicate possible methods to be de- 
veloped. The use of impingers or filters is recom- 
mended when numerical values of the MMD or 
impactibility are not required. The total chemical Ct, 
without regard to size, can be measured for dry par- 
ticulates with filters. Rayon-asbestos, esparto-as- 
bestos, and gas mask filter papers may be used. For 
use with W these papers are unsuitable owing to the 
strong adsorption of the protein on the paper. Cellu- 
lose acetate filter batts do not absorb proteins and 
in addition are soluble in appropriate organic liquids. 
Another qualitative device for evaluation of aggre- 
gates is the “sticky finger.” 

Methods have been developed and results obtained 
during the period 1941 to 1945 which indicate the 
desired particle size for various purposes. In the same 
period, however, no adequate munition capable 
either of producing such sizes or dispersing materials 
already prepared at those sizes has been developed. 
Thus, at the date of writing, W (which has in the 
laboratory several score times the toxicity of phos- 
gene) has (in the field) been found to be only seven 
times as toxic as phosgene in the best munitions 
available.^® 


SECRET 


Chapter 16 


APPARATUS AND TECHNIQUES UTILIZED IN TOXICOLOGICAL 
STUDIES ON CHEMICAL WARFARE AGENTS 

By H. A. Wooster and W. L. Doyle 


16.1 INTRODUCTION 

I N THIS CHAPTER are summarized methods de- 
veloped and utilized for toxicological studies at 
the University of Chicago Toxicity Laboratory 
[UCTL]. Pertinent contributions of other NDRC 
Division 9 contractors are included, but no attempt 
is made to review systematically developments made 
by other agencies. 

The apparatus and methods are described under 
the following major headings: (1) gassing chambers, 
(2) methods of dispersing agents into chambers, 
(3) sampling equipment, (4) precision methods of 
testing inhalation toxicity, and (5) methods of test- 
ing vesicants. Each section starts with a discussion 
of the relevant principles and is followed by a brief 
description of specific items of equipment and pro- 
cedure, together with an evaluation of the merits and 
limitations of each. Descriptions and construction 
details for the more important items of equipment 
will be found in the reports listed in the Bibliography 
and referred to in the text. 

The work leading to the development of appara- 
tus included in this report was initiated prior to 
March 15, 1945, at which time the contract with the 
University of Chicago was assumed by the Chemical 
Warfare Service. Subsequent work has been reported 
where it was in logical extension of apparatus initi- 
ated under the prior contract. 

16.2 GASSING CHAMBERS 

16.2.1 General Description of Design 
The earliest form of gassing chamber was a closed 
container in which the animals were placed and the 
agent dispersed. Despite the simplicity of such an 
apparatus, its use introduces many complexities. 
The actual concentration of agent in it at any one 
time is a result of the action of at least two variables 
— the rate at which the agent is sprayed into the 
chamber and the decrease of the concentration. The 
latter is influenced in several ways — absorption on 
the chamber walls, chemical changes of the agent 


(the hydrolysis of dichlordi alkyl arsines, for exam- 
ple), and, in the case of particulates, aggregation of 
the smaller particles. Animals kept in a closed cham- 
ber for any period of time may change the carbon 
dioxide content of the air sufficiently to distort their 
respiratory patterns. Nominal concentrations in such 
chambers are almost meaningless, and analytical 
concentrations are difficult to interpret. 

Lehmann, in Germany, in a long series of investi- 
gations (1884-1913) studied the effects on animals of 
various toxic vapors used in industry. His method 
was to expose animals in a modified Pettenkofer 
respiration apparatus to a continuous flow of air con- 
taining a constant and known concentration of the 
agent being studied. Almost all the gassing chambers 
used in this country since 1918 are based on this 
constant flow, or “dynamic’’ principle. (It should be 
noted that English workers, in many of their screen- 
ing runs, employed “static” chambers during World 
War 11.) 

The ratio of chamber volume to air flow is critical 
in the design of such chambers. Silver derives the 
basic equation covering chamber equilibration times: 

h, = 4.6 X y 
0 

where ^99 = time for the chamber concentration to 
attain 99 per cent of the theoretical 
nominal concentration. 
a = volume of the chamber in liters. 
b = the rate of air flow in 1pm. 

It will be seen from this that a chamber having an 
air flow of 1 chamber volume per minute will come to 
equilibrium in about 5 minutes; with 10 chamber vol- 
umes per minute equilibrium is attained in 0.5 min- 
ute. A quick equilibration time has several advan- 
tages — momentary changes in concentration, such 
as those produced by the introduction of animals, are 
quickly rectified, and unstable materials have less time 
in which to decompose. The saving in material by the 
use of a shorter equilibration time is overbalanced 
by the larger amount of material necessary to set up 


278 


SECRET 


GASSING CHAMBERS 


279 


a given concentration, but a 5-g sample is generally 
adequate for a single test of a substance toxic at 
0.3 mg/1. When slowly volatile materials, which exist 
as both vapors and aerosols, are dispersed in cham- 
bers of very high flow rates, such as the auxiliary 
chamber for the 200-1 medium flow chamber (see 
below), effects of the flow rate on toxicity may be 
encountered. 

The flow of air through the chamber may be pro- 
duced by either positive or negative pressure. In 
most chambers negative pressure is used, to mini- 
mize the tendency for toxic materials to escape into 
the laboratory. Standard equipment for this is a 
gear-type (Roots) blower V-belted to an electric 
motor. An air ejector is used on the chamber for the 
large Benesh atomizer, and water aspirators have 
been used on some small smoke chambers. Positive 
pressure has been used on three chambers — a large 
screening smoke chamber, a small chamber used for 
testing the toxicity of gasoline, and the microline. 
In these chambers the air flow is controlled by the 
volume of air blown into the chamber. 

Standard equipment for measuring air flow 
through the larger chambers has been an orifice in a 
Monel plate in the effluent line between the chamber 
and the filters. A differential manometer, filled with 
butyl phthalate, is connected to each side of the 
orifice. To calibrate such a flowmeter a large dry- 
type gas meter is connected to the chamber and all 
other openings are sealed. A working calibration 
chart is prepared from these readings. The dry meter 
is calibrated by positive displacement of a measured 
volume of air. 

The standard orifices are about 0.8 inch in diam- 
eter. Because of their location they are subject to 
contamination and corrosion. When aerosols are used 
in the chamber they tend to clog up the hole and 
make it smaller. It is advisable to recalibrate such 
orifice flowmeters at least once a year. A much larger 
orifice (about 2.5 inch) has been used in the chamber 
for the large Benesh atomizer, which was designed 
specifically for use with smokes. An inclined differ- 
ential manometer is necessary to read accurately the 
small pressure gradient resulting from the use of such 
a large orifice. 

The effluent from these chambers contains a large 
proportion of the original toxic material. It is passed 
through replaceable charcoal filters. When nonvola- 
tile vesicants have been used, the filters become 
heavily contaminated, and their removal and re- 
charging is a hazardous procedure. The effluent from 


all chambers plus the effluent from all rooms is drawn 
off by rotary blowers and discharged into a large 
incinerator stack. The dilution afforded by the stack 
provides a larger margin of safety and in some cases 
permits dispensing with charcoal filters. The UCTL 
stack has an average inside diameter of 163^ feet 
and is 100 feet high. Under normal conditions the 
stack discharges 750,000 cfm. 

The chambers are of metal and/or glass construc- 
tion. The all-metal chambers are constructed of 
welded ^Q-inch mild steel plate, which is protected 
on the inside with a baked-on vitreous or bakelite 
resin (Lithcote) enamel. Connections to these cham- 
bers are made with standard plumbing pipe fittings. 
Ten-liter wide-mouth glass bottles with holes drilled 
in them have been used for several small chambers. 
The chamber on the small Benesh machine is made 
entirely of triplex safety glass, cemented together. 
Composite structure is represented by the 400-1 
chamber, made from a length of Pyrex industrial 
pipe 12 inches in diameter, fitted with brass ends, 
and the 488-1 chamber, made of metal lined with 
plate glass. 

One of the more important procedures in gassing 
animals is the method of introduction of animals into 
the chamber. The simplest method, which is entirely 
feasible with mice, is to open a port and insert the 
caged animals. This is routinely done with the small 
smoke chambers and with some of the larger cham- 
bers which have small auxiliary ports on their larger 
doors. With larger animals, some sort of sliding car- 
riage for the cages must be provided. This is, in 
essence, a three-sided box, the ends of which are 
plates, and the bottom an open structure. The side 
view can be represented by L! Either end may 
serve as a closure for the opening in the chamber side. 
When such a carriage is rapidly pushed into a cham- 
ber, a certain piston action is exerted. The carriage 
on the big Benesh machine was designed to avoid 
this. When the carriage is out of the chamber, closure 
is provided by a vertically sliding glass panel. Thus 

the carriage needs only the form |. In high-flow 

chambers the animals may be placed in the chamber 
before the agent is put in. This is practicable because 
of the short equilibration time of such chambers. 
However, it should not be used for short exposures to 
substances which deviate markedly from Haber’s 
law. 

One difficult problem in the design of chambers is 
the position of the port through which the agent is 
to be introduced. This may be at either the top or 


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280 


APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


the side of the chambers. The top is a somewhat more 
convenient location, inasmuch as all the parapher- 
nalia connected with dispersal may be placed on top 
of the chamber out of the way. When dealing with 
gases or with aerosols set up by a baffled atomizer, 
the position is not so important as with other de- 
grees of dispersion because the materials enter the 
chamber at a low velocity and loss by impaction on 
inlet tubes is negligible. With concentric atomizers 
dispersing semivolatile materials, introduction from 
the top means that the spray must undergo a right- 
angle bend to get into the chamber, with consequent 
loss on the mixing bowl. A jet fed in from the side of 
the chamber must be aimed with care to clear the 
animal cages. It would seem advisable to design 
future chambers with provision for the optional use 
of either route of entry. 

Little attempt has been made so far to control the 
temperature and humidity of air entering the cham- 
ber. In most cases the chambers withdraw air from 
the laboratory and operate at the ambient temper- 
ature and humidity. In the microline provisions were 
made to humidify the entering air. Some small cham- 
bers have been operated in a thermos ta ted water 
bath. The most elaborate regulation is in the man- 
chamber, which has automatically controlled equip- 
ment for heating or cooling, and varying the water 
content of the entering air, as well as temperature 
control of the room surrounding the chamber. 

16.2.2 Description of Specific Chambers 
Rectangular Chambers Larger than 200 Liters 

Jf-OO-Liter Standard Chamber The first large 
chamber used at UCTL was built from a design 
standard at Edge wood Arsenal. This chamber is 
fitted with a sliding carriage 8 inches high and 15 
inches wide. This, at most, can hold 4 cats or rabbits, 
or 20 guinea pigs or rats. The chamber air flow can 
be regulated between 50 to 90 per cent of the cham- 
ber volume per minute. A wooden sliding carriage 
with stocks for surrounding the necks of exposed 
animals was made to study body and head exposures. 

In use, this chamber was found to have several 
limitations. Animals larger than cats could not be 
exposed routinely (single dogs were used in body ex- 
posures). Appreciable difficulty was encountered in 
working with lewisite, owing to wall loss at the low 
flow rates — e.g., the nominal LC^q of lewisite for 
mice was approximately three times as high with the 
standard chamber as with the Benesh machine. 

880-Liter Standard Chamber.^ This chamber is 


identical in principle and operation with the 400-1 
chamber. The sliding carriage is somewLat higher in 
relation to the height of the chamber. Its cross- 
sectional dimensions are 23x55 inches. This gives 
it a maximum animal capacity of 4 small dogs, or 
2 large dogs, or 1 or 2 goats, or 6 monkeys. A mixed 
group of 1 small dog, 4 rabbits, 4 cats, 10 guinea pigs, 
10 rats, and 20 mice can be exposed at the same time. 

At a later period a small door was built into the 
outside plate of the sliding carriage, making it possi- 
ble to put small animals into the chamber without 
pulling out the carriage. 

This chamber has been calibrated with mustard 
gas (H), using the Northrup titrimeter.^^^ The air 
flow was 700 1pm, and the nominal concentration 
may be expected to be in error by about + 5 per cent. 
The concentration built up is the same in all parts of 
the chamber within 1 per cent and the drop in con- 
centration on moving the carriage in or out is prob- 
ably not more than 5 per cent. 

This chamber has, perhaps, been the most con- 
sistently useful for general work. 

200-Liter Medium Flow Chamber}^ This chamber 
was designed to provide a chamber in which dogs and 
other large animals could be exposed to agents at 
rates of chamber exchange comparable to those at 
which mice had been exposed in smaller chambers. 
By interchanging a glass door on the side of the 
chamber for one which is provided with platforms 
and head stocks, mice, rats, or guinea pigs may be 
exposed to gases either by inhalation or by body ex- 
posure alone. A similar arrangement can be attached 
to the front carriage for similar exposures of cats, 
rabbits, or dogs. 

Some time after the chamber was built an auxiliary 
high-flow chamber was added. The new chamber 
was built onto a removable side plate which could be 
substituted for the side door. The cross-sectional 
diameter of the high-flow chamber is about one-ninth 
that of the main chamber. Air is drawn from the 
main chamber into the auxiliary chamber and thence 
into the exhaust line. When the chamber is operated 
at 500 1pm, the velocity is increased to 3 mph just 
before the toxic agent reaches the animals, with a 
minimum velocity of 0.5 mph in the center of the 
compartment in which the animals are exposed. 
These velocities may be increased or decreased by 
varying the air flow. The incident velocity may be 
changed by changing the size of the slits through 
wfflich the air stream enters. 

The high-flow chamber is 18x7x3 inches. It 


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GASSING CHAMBERS 


281 


is divided into three compartments by two longi- 
tudinal walls, each of which contains 10 slits, 2x 
]/2 inches. The slit size may be varied. The compart- 
ment in which the animals are exposed is 18x3x3 
inches, and is located between the other two com- 
partments. The long, slender compartments on each 
side have openings in the floor through which ana- 
lytical samples may be drawn. The inner of the small 
compartments is open on the side communicating 
with the main chamber, and on the distal side has the 
slotted wall openings. It serves as a mixing chamber 
to insure that all the animals are exposed to the same 
concentration. The outer of the two compartments 
has a slotted inner wall through which the air stream 
leaves. The effluent is carried away through an open- 
ing in the end of this chamber. Analytical samples 
can be drawn before and after the agent passes the 
animals. 

Animals may be exposed by total exposure, or by 
body or head exposure alone. A special manifold is 
provided for the last two types. The lower portion of 
the side plate to which the high-flow chamber is 
attached can also be used for either body or inhala- 
tion exposures at low flow rates. Total exposures for 
low flow rates can be carried out by placing animals 
in the main chamber. Animals may, therefore, be 
exposed simultaneously to high and low flow rates 
either by total exposure, body exposure, or inhalation 
exposure. 

The 200-1 chamber differs in several design details 
from the standard chambers. The carriage is provided 
with castors, making it more convenient to slide it in 
and out. In the standard chambers the bare metal of 
the door seats against the bare metal of the chamber. 
In this chamber sponge rubber gaskets are pro- 
vided. The toxic agent is usually admitted at the top 
of this chamber instead of at the side. 

In the use of this chamber a good agreement has 
been obtained between analytical and nominal con- 
centrations. L{Ct)BoS obtained by this chamber cor- 
respond with those obtained in the small high-flow 
chambers. This is not the case with values obtained 
from the 400-1 standard chamber. 

429-Liter Glass-Lined Chamber. This chamber was 
designed specifically for use with aerosols. It is lined 
with plate glass. The sliding stainless-steel animal 
carriage is attached to a glass panel which forms the 
front wall of the chamber when the carriage is in 
place. When this is not used a counterweigh ted glass 
panel drawn down from the top seals the chamber. 
Interlocks are provided so that the carriage cannot be 


pushed in until the sliding panel is fully raised. This 
scheme is a trifle complicated and requires two oper- 
ators for rapid action, but has the advantage that it 
does not exert the plunger effect of the usual cham- 
ber carriage. A small circular auxiliary port in the 
panel on the carriage permits caged mice to be placed 
in the chamber without opening the main door. 

A large air injector is used as a pump to exhaust 
air from the chamber. This gives a maximum air flow 
of 900 1pm at 35 lb air pressure. An inclined differen- 
tial manometer, reading across a large orifice, gives 
the chamber air flow. Such a large orifice is less sensi- 
tive to fouling than those commonly used. The air 
injector is also less subject to fouling with aerosols 
than gear- type blowers. Variations in the pressure of 
the air running the Venturi are corrected by a 
diaphragm-actuated regulator. 

The glass lining makes this chamber particularly 
easy to clean. It is much quieter in operation than 
the mechanically driven chambers. 

This chamber has been calibrated with H by means 
of the Northrup tit rime ter, at a nominal concentra- 
tion of 38.8 )Ug/l and an air flow of 1.5 chamber vol- 
umes per minute. The following conclusions were 
drawn : 

1. The Ct calculated from the nominal concentra- 
tion will be in error by about +16 per cent. 

2. The 10-minute Ct calculated from an analytical 
concentration measured at about the mid-point of a 
10-minute exposure will be in error by about ± 3 per 
cent. 

3. The Ct calculated from an analytical concen- 
tration based on a sample drawn over the entire 
period should be in error by less than 3 per cent. 

4. In general, errors caused by the fall in concen- 
tration that occurs upon pushing in the animal cages 
may be neglected for 10-minute exposures and can be 
corrected by analytical samples drawn at intervals 
during the entire exposure period. 

Screening Smoke Chamber . This chamber was 
designed for the repeated exposures of animals to low 
concentrations of agents employed as screening 
smokes. It was made large enough for monkeys to 
live in and was fitted with automatic controls. The 
chamber is 4 feet square and 7 feet high. Its volume 
is 3,078 1. The base is a concrete block fitted with a 
drain and lined with sheet metal. The top is wooden, 
as are the corner posts. The sides are of glass. A com- 
mon wooden door with a glass panel is let into one 
side. This door is weatherst ripped. The whole struc- 
ture is lined with a very heavy wire mesh. 


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282 


APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


Two fans are used with this chamber. A continu- 
ously running exhaust fan provides ventilation. An 
intermittently operating centrifugal blower giving 
2,180 1pm is mounted on the top of the chamber. Just 
below the ceiling outlet is a suspended baffle plate. 
A six-jet atomizer (DeVilbiss experimental model 
No. 7030-1), connected to the compressed air line, 
discharges into the inlet of the centrifugal blower. A 
General Electric time switch controls the solenoid 
valve, feeding compressed air to the atomizer and the 
relay actuating the inlet fan. These go on and off to- 
gether, in a cycle of 30 minutes on and 30 minutes 
off. 

The chamber was found to come to equilibrium in 
10 ( ± 2) minutes. This is somewhat longer than the 
theoretical time. Forty-five per cent of the equi- 
librium concentration is reached after 1 minute, 
and eighty per cent at 5 minutes. 

Lacrimator Chamber This chamber is essentially 
a 400-1 standard chamber with a maximum air flow 
of 1,000 1pm. The adaptation for use with lacrimators 
consists of three ports projecting from the center of 
the chamber walls on three sides. Eye pieces, which 
fit the ports snugly, consist of rubber diaphragms 
edged with rubber tubing. Swimming goggle frames 
are cemented around holes cut in the diaphragm. 
The sternutator provision consists of industrial-type 
nose and mouth respirator masks connected to the 
chamber with lengths of gas mask hose. There are 
six of these. 

The subjects signal their response by tapping keys, 
located under the ports, which cause signal magnets 
to mark an automatically timed rotating kymo- 
graph. The subject taps the key when irritation is 
first experienced, and again when he feels tears start- 
ing to form. Thereafter he depresses the key each 
time he is forced to close his eyelids and releases it 
when the lids are once again open. At the end of the 
run there is a graphic record of the onset of irritation 
and of lacrimation, as well as of the periods during 
which the eyes were open or closed. 

Owing to the low priority assigned to lacrimators 
and sternutators, this chamber was never extensively 
used or completely calibrated. 

Great Lakes Man-Chamber This cham- 
ber was designed for the exposure of human subjects 
under conditions of temperature and humidity con- 
trollable by the investigator and independent of 
ambient conditions. 

The chamber is made of ^^-inch boiler plate, lined 
with ^6-inch sheet lead. Its volume, exclusive of 


the air lock, is about 17,300 1. The maximum flow 
rate through the chamber is about 5,100 1pm. All 
control of concentration (H has been the only agent 
used) is done with the Northrop titrimeter, so that 
exact values for this flow are not so necessary as when 
an attempt is made to estimate the nominal con- 
centration. 

This chamber is equipped with automatic pneu- 
matic controls for temperature, relative humidity, 
rate of flow, and pressure. They function as follows: 

1. All air coming into the chamber passes through 
a commercial air-conditioning unit. It emerges from 
this into the chamber at 26 F, saturated with water 
vapor. When warmed to 70 F, this air is at about 
35 per cent relative humidity. The temperature and 
relative humidity of this air represent the lowest 
levels at which the chamber can be operated. 

2. The desired wet bulb and dry bulb tempera- 
tures are set on the controlling-recording apparatus 
and the steam lines are opened. Heating is controlled 
by a steam coil controlled by the dry bulb tempera- 
tures. Lowered wet bulb temperatures cause the 
automatic humidity valve to open, injecting steam 
into the chamber. When the wet and dry bulb tem- 
peratures reach the desired values, the humidity 
valve closes and the by-pass dampers open ; thus the 
incoming air is conducted underneath the heating 
coil rather than through it. 

3. When the air is pulled through the heating coil, 
there is more resistance in the system than when the 
air is by-passing the coil, so that adjustments of the 
flow are necessary. This regulation is controlled by 
dampers on the discharge side of the exhaust fan. 
When the flow rate drops below 5,600 1pm, these 
dampers open and permit more air to be drawn out 
of the chamber; as the flow rate rises, the dampers 
close and cut down the flow. The flow rate usually 
oscillates between 5,300 and 5,900 1pm. 

4. Ordinarily the fluctuations in the amount of 
air discharged would produce variations in the pres- 
sure inside the chamber. Such variations are elimi- 
nated by automatic control of the dampers on the 
discharge side of the supply fan. The pressure con- 
troller is set for a differential of 0.1 inch of water; 
when the pressure in the chamber increases, the con- 
trol damper effects an opening of the dampers to the 
room, so that less air is passed into the chamber. 
Similarly, when the inside pressure falls to a value 
lower than 0.1 inch of water below the outside pres- 
sure, the dampers close to permit a larger volume of 
air to enter the chamber. 


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GASSING CHAMBERS 


283 


An air lock is equipped with motor-driven ports by 
means of which fresh air may be diverted through the 
air lock when men wearing contaminated clothing 
are leaving the chamber. 

Measurements of the wind speeds in the chamber 
showed that the velocities vary from less than 
0.4 mph in the corners to over 8 mph in front of the 
fans, with an average of 2.5 mph for 32 positions. 

Constant-Flow Chambers Smaller than 100 L 

The Microline} The 400- and 800-1 standard cham- 
bers were found to be unsuited for ‘‘screening” new 
agents of which only small amounts were available, 
and for working with unstable substances such as the 
arsenicals. The microline together with its ancillary 
chambers was designed to provide a small chamber 
through which a relatively high flow of air at con- 
trollable humidity could be sent. 

The influent air is delivered via two parallel series 
of bubblers and absorbers. One of these delivers dry 
air, the other saturated. These are mixed in the de- 
sired proportions and passed through a dispersing 
bubbler or an impinging atomizer containing the 
agent and thence into the chamber. 

The first chamber used with this microline was a 
10-1 screw-capped wide-mouthed bottle. A cylindrical 
cage fastened to the bakelite screw cap contained six 
mice. A U-shaped manifold, both ends of which 
passed through the screw cap, was used for body ex- 
posures. The heads of mice were stuck through holes 
in the manifold while fresh air was circulated through 
it, and a concentration of toxic agent was set up in 
the chamber. A branched manifold for testing toxic- 
ity by inhalation could be substituted for the cham- 
ber. This enabled 8 mice to inhale the agent while 
their bodies were exposed to room air. 

These chambers and manifolds had several draw- 
backs. Only mice could be used in the chamber, and 
not more than six of these. The agent flowed linearly 
through the chamber, so that if the first animal af- 
fected the composition of the agent the last might 
get a lowered dose. The inhalation and body expo- 
sure manifolds could hold only 8 and 6 mice, re- 
spectively, and were difficult to manipulate. 

Later a commercial Lectrodryer unit® was in- 
stalled to supply adequate amounts of dry com- 
pressed air. The size of the water-saturaters was in- 
creased proportionately. An 11.5-1 chamber was con- 
structed of plate glass cemented together and sup- 
ported inside of an angle iron framework. This was 
designed to assure equal distribution of the toxic-air 


mixture directly to each animal. To do this the 
material is conducted into an H-shaped channel, 
each arm of which has an opening connected with a 
slit in the glass side of the chamber, 0.1 mm wide and 
extending from front to back. The channel is de- 
signed to give uniform flow through the whole length 
of both slits, which form two horizontal lines on each 
side of the chamber and are so centered that, when 
the mouse cage is placed in the chamber, the animals 
are directly opposite the slits in line with the flow of 
the material. This permits a high degree of uniform- 
ity in exposure of the mice. The effluent is carried off 
by an identical a rrangement on the other side of the 
chamber. This chamber has a capacity of 20 mice, 
3 rats, or 3 guinea pigs. 

A body exposure manifold which holds 20 mice and 
fits into the chamber and a separate inhalation mani- 
fold holding 16 mice have also been constructed. 

Using an aerosol of HN3, recoveries of about 65 per 
cent were obtained from the chamber in the absence 
of animals and of about 75 per cent from the inhala- 
tion manifold. Recoveries of more volatile materials 
are well above 90 per cent. 

Small Smoke Chamber. This was essentially a vastly 
simplified microline. Dry air was passed through a 
dispersing bubbler or impinging atomizer. The re- 
ducing valve on the compressed air tank, with the 
atomizer connected, was calibrated in liters per min- 
ute versus pressure. Auxiliary air could be bled in 
through a Y tube to bring the flow to the desired 
value. The air flow was then led thfough a water or 
steam jacketed condenser into the wide-mouthed 
bottle used as a gassing chamber. The toxic material 
was blown out of the chamber into the air of the 
hood in which the whole setup was placed. This 
chamber has been used in a thermostated water bath 
for exposures above or below room temperatures. 

This setup, which required a minimum of appara- 
tus, proved to be quite useful for screening materials 
of low vapor pressure. Its use was limited to materi- 
als which would melt without decomposing, so that 
they could be dispersed with an impinging atomizer. 
Mice, guinea pigs, and rats were the only animals 
that could be fitted into the chamber. 

A modification of this chamber was used to set up 
very high concentrations of gasoline vapor.^^® All air 
entering the chamber was blown through a concen- 
tric atomizer, and then passed through a steam- 
heated Friede rich’s condenser. A trap in the line re- 
moved nonvolatilized material before it entered the 
chamber. 


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284 


APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


Specialized Chambers 

The Explosion Chambers. Chambers were required 
to assay the action of high explosives on the toxicity 
of certain chemical warfare agents. It was necessary 
to construct a rugged chamber in which small 
amounts of explosives could be set off and the toxicity 
of the resulting airborne material assayed. 

The first of these was a 1-ton shipping container 
for war gases such as mustard. A port (12-inch di- 
ameter) was welded on this. It was fitted with a steel 
cover 2 inches thick, bolted down with 1-inch bolts. 
This chamber was used while a specially designed 
chamber was being built.^^^ 

The latter was constructed from 18-8 stainless 
steel. The interior is polished to a No. 4 finish. The 
vessel is 48 inches in outside diameter and approxi- 
mately 8 feet high. The volume is 2 cu m. It is 
mounted over a concrete pit in a specially constructed 
laboratory and is shielded by heavy concrete walls. 
The dome-shaped top of the chamber is held down 
by 80 bolts under spring tension to act as a safety 
valve yielding at 80 psi. Easy access to the interior is 
provided by an 18-inch manhole with single-screw 
closure. There are eight 4-inch ports which can be 
closed with ^^-inch Pyrex or stainless-steel plates; 
additional ports are provided for valves and electri- 
cal leads. The chamber is equipped with a shower for 
flushing. The walls and interior fittings are designed 
to permit complete drainage to the valve at the bot- 
tom. This permits maximum recovery of the prod- 
ucts. 

Steam lines lead to the chamber for decontamina- 
tion. The residual gases in the chamber may be 
drawn through a 200 cfm collective protective 
canister. 

When metal bombs are exploded they are sur- 
rounded by stainless-steel baffles to protect the walls 
of the chamber. This is not necessary for glass or 
plastic bombs. The resultant gas-smoke mixture is 
drawn through Pyrex glass piping to a small glass 
constant-flow exposure chamber. The effluent from 
the exposure chamber is filtered and absorbed in the 
usual fashion. 

This chamber is somewhat small for testing the 
effects of high explosives on chemical warfare agents. 
Twenty-five grams of explosive is the maximum that 
can be detonated. It would be desirable to have 
means of heating and cooling the chamber walls. 
Other than this, the chamber has proved quite satis- 
factory. It is the only known explosion chamber per- 
mitting recovery and analysis of the entire residue. 


The Wind TunneU^^ The UCTL became inter- 
ested in the relation of particle size to vesication on 
bare skin and through clothing and in the relative 
efficiencies of the vapor and aerosols of the same ma- 
terial as vesicants. It was necessary to construct a 
wind tunnel in which the arms of human subjects 
could be exposed to airborne agents moving at vari- 
ous and variable velocities. 

The tunnel, circular in cross section, is 14 feet long 
and 2}/2 feet in diameter in the largest places. It is 
fashioned after certain Porton models designed to 
give an even distribution of droplets across the work- 
ing section. It differs from streamline tunnels, in 
which markedly higher velocities exist at the center 
of the stream than at the edges. 

The wind tunnel proper (Figure 1) is of cylindrical 
cross section. Two truncated cones {B and C) are 
placed base to base with a short base diameter cylin- 
der in between. This assembly precedes a longer 
cylindrical section (Z)), 18 inches in diameter and 
3 feet long. The source of vapor or particulate spray 
is an atomizer or bubbler orifice located at the mouth 
of the tunnel. In order to mix the narrow plume of 
agent with the main air stream, the diameter of the 
tunnel is increased {B) to produce turbulence. The 
expanding cone is followed by a reducing cone (C) to 
give approximately constant velocity across the 
stream in the cylindrical working section (D). The 
flow through the working section is somewhat turbu- 
lent at 7 mph. This turbulence can be decreased by 
placing a hardware cloth screen in the reducing cone, 
but such a screen causes an increase in concentration 
of the larger particulate droplets in the center of the 
stream. Without the screen the droplet distribution 
is quite homogeneous across the tunnel. Turbulence 
creates vortexes in the working section, producing 
differences of about 10 per cent (at 7 mph) in the 
velocities at opposite sides. This difference could 
probably be decreased by increasing the length of the 
cylindrical section between the two cones B and C. 
With particulate clouds of nonvolatile droplets in 
which 30 per cent of the mass is in the size range 
10-30 fx, there is a just perceptible loss on the walls; 
the loss is negligible with smaller droplets. With drop- 
lets of 150 ±50 in diameter there is a slightly 
greater loss on the bottom of the tunnel than on the 
top. Most of the loss occurs in the reducing cone (C). 

The source of suction is the room ventilation which 
leads via filters to the incinerator stack. The flow is 
regulated by adjustable louvers. To obtain velocities 
above 25 mph a tube with its own reducing cone and 


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METHODS OF DISPERSING AGENTS INTO CHAMBERS 


285 



B Expansion cone. E Removable, high velocity, reducing cone. 

C Reducing cone. F Velocity control damper. 

G Exit to stack. 

Figure 1. Wind tunnel, elevation. 


smaller working section is available. Fairing of the 
incoming air stream is accomplished with a commer- 
cial “anemostat’’ with the three central vanes re- 
moved. The working section is provided with a door, 
windows, and sampling ports for introduction of 
animals, arms, and instruments. Air speeds are meas- 
ured with a commercial Velometer. 

The wind tunnel has been employed in studies on 
vesication by particulates and in the development of 
methods of assessment of particulates (see Chap- 
ter 15). 

16.3 METHODS OF DISPERSING AGENTS 
INTO CHAMBERS 

16.3.1 General 

Liquids may be dispersed as vapors or as aerosols. 
Solids may have been previously comminuted or it 
may be required to subdivide them in the process of 
dispersal. The choice of method to be employed 
should be based on the following criteria. 

1. The dispersing technique must not produce any 
chemical change in the material. 

2. The delivery rate must be constant during the 
experiment. 

3. The rate of delivery should be readily measur- 
able in order to provide a measure of the nominal 
concentration. 

4. The rate of delivery should be readily adjust- 
able to provide an adequately wide range of con- 
centration. 

5. The material must be dispersed in particles of 
desired size. 


16.3.2 Techniques of Dispersal 

The UCTL has had to test the toxicity of materi- 
als ranging in volatility from gases to metals. The 
physical state of a substance determines the method 
of dispersal to be used. 

Compounds Boiling Below 0 C.® These substances 
are usually available compressed in small steel or 
copper cylinders. A pressure-reducing valve is at- 
tached. A capillary or orifice flowmeter is then cali- 
brated for the rate of flow of the gas by the liquid 
displacement method. A liquid in which the gas is 
insoluble is used in the flowmeter as well as in the 
pneumatic trough. The gas is delivered at the desired 
rate through the flowmeter directly into the gassing 
chamber. A nominal concentration, as a check on 
that derived from the rate of flow, is obtained by 
weighing the cylinder before and after each run. Un- 
stable gases (e.g., ketene 2 ^^) have been generated 
directly into the chamber. 

Liquids Boiling Between 0 C and Room Temper- 
ature. These compounds may be dispersed as gases 
or, with proper cooling, as liquids. If they are to be 
treated as gases they are distilled into a glass am- 
poule. A calibrated flowmeter and a reducing valve 
are attached as described. The nominal concentra- 
tion is obtained by determining the volume dis- 
placed during a run or by weighing. 

It is usually more convenient to treat such com- 
pounds as liquids. With proper cooling, a solution 
may be made up. Any dispersing device for liquids 
which can be adequately chilled can then be used. 
Such devices are concentric and impinging atom- 


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286 


APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


izers, bubblers, and the small Benesh and constant- 
delivery atomizers. 

Liquids Boiling Above Room Temperature. These 
may be dispersed by vaporizing or spraying. They 
are vaporized by passing nitrogen through a bubbler. 
The volatility of the material determines the size of 
bubbler and the degree of heating or cooling required. 
In general it is desirable to use as little heating as 
possible. Heat is supplied by a water bath at a tem- 
perature somewhat higher than that desired for the 
liquid in the bubbler. 

Liquids may be atomized either undiluted or in 
solution. Solutions should not be dispersed from im- 
pinging atomizers since the solute and solvent are 
usually refluxed to different degrees with correspond- 
ing changes in concentration of the solution in the 
atomizer. 

Solids Which Can Be Dissolved or Which Melt with- 
out Decomposition. A solution of a solid can be 
sprayed in the usual fashion. The volatility of the 
solvent is important. If too volatile it may evaporate 
sufficiently rapidly at the atomizer tip to produce 
clogging. 

Agents which melt without decomposition can be 
dispersed from a direct or impinging atomizer im- 
mersed in a water or oil bath. 

Solids Which Cannot Be Dissolved and Which De- 
compose When Melted. In most cases these materials 
must be ground to the desired particle size before 
dispersal. They can be dispersed from the dry duster 
(see Section 16.3.3 under “The Dispersal of Par- 
ticulates”). 

Very fine aerosols of metals have been produced by 
means of an high-tension arc, using the metal as one 
of the electrodes. 

16.3.3 Apparatus for Dispersal 
Dispersing Bubblers 

A method of dispersing liquids with appreciable 
vapor pressures is to bubble a nonreactive gas 
through them. The output is controlled by varying 
the flow of the gas and the temperature of the water 
bath in which the bubbler is immersed. The gas pass- 
ing through the liquid is broken up into small bubbles 
by passage through a sintered glass disk (coarse 
porosity) or a Folin bulb. 

The type of bubbler used depends on the volatility 
of the toxic agent. Agents boiling below 50 C are kept 
in bubblers with stopcocks at both inlet and outlet to 
minimize the possibility of leakage when the bubbler 
and contents are being weighed at room tempera- 


ture. Compounds with high boiling points are kept 
in bubblers with outlets large enough that the rapid 
flow of the gas mixture does not blow out material 
condensing in the outlet nozzle. When small amounts 
of agent are to be dispersed the bubbler should be 
kept small and light enough to be weighed on an 
analytical balance. (This also applies to atomizers.) 

When substances are vaporized from bubblers it is 
desirable to keep the bath temperature as low as 
practical. This minimizes the decomposition of ther- 
molabile agents. To get high concentrations in such 
cases increased gas flows are employed in large 
bubblers through which as much as 12 1pm of gas 
can be passed. 

The use of bubblers in toxicity determinations is 
limited by the purity of the substance available and 
the amount of air (or nitrogen) which can be passed 
through them. If the toxic material is quite pure and 
stable the amount of substance volatilized per vol- 
ume of gas passing through is quite constant. A very 
slight degree of impurity will, if the impurity is 
volatile, result in a changing output from the bubbler. 
As a result it is always necessary to make a series of 
preliminary runs to bring the output down to “con- 
stant volatility.” Bubblers designed to hold 10 to 
50 ml of toxic agent usually permit the passage of 
gas at a maximum flow rate of 2 1pm. The most con- 
stant operating conditions are obtained when the 
rate of gas flow through the bubbler is sufficiently 
slow to permit at least 95 per cent saturation of the 
gas with the vapor. 

Atomizers 

An atomizer functions on the Bernoulli principle. 
A tube is positioned in the center of a jet of air. This 
tube is immersed in the liquid to be dispersed. The 
liquid is aspirated up the tube and sheared off the 
end. The size of droplets produced depends on the 
diameter of the tubing at its orifice, the viscosity of 
the liquids, and the rate of flow of air. The tube sup- 
plying liquid may be concentric with the jet of air or 
at right angles to it. 

Concentric Atomizers.^ These are commonly made 
of glass. A capillary tube {A, Figure 2) is drawn 
down to a tip and bent at right angles and sealed into 
a bulb B. The tip of the capillary is adjusted so that 
it is precisely centered in the orifice 0 of the bulb. 
The annular space between the orifice 0 and the tip 
of the capillary is drawn to such dimensions that the 
desired delivery is obtained at air pressures of 5 to 
20 psi. 


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METHODS OF DISPERSING AGENTS INTO CHAMBERS 


287 


H 



O Orifice. 

Figure 2. Concentric atomizer. 

Maximum efficiency is obtained when the tip of 
the capillary either extends slightly beyond or is 
withdrawn slightly into the outer orifice. The adjust- 
ment is most readily made by heating the atomizer 
in the region of H (Figure 2). 

The delivery rate and particle size are determined 
by the dimensions of the tip and the orifice. 

A constant head device can be applied to the flask 
so that the delivery does not vary with the level of 
the fluid. 

Concentric Atomizers — Constant Delivery Type. 
Concentric atomizers supplied with liquid solely by 
the Bernoulli effect are subject to variations in their 
delivery rate. The delivery rate decreases as the 
liquid level falls. Furthermore, the delivery rate is 
influenced by fluctuations in pressure of the gas 
driving the atomizer. At the UCTL certain atomizing 
units have been constructed which are provided with 
liquid by a constant-flow motor-driven pump. Two 
of these are called Benesh machines, after M. E. 
Benesh, Chief Engineer in charge of Research and 
Testing of the People’s Gas, Light and Coke Com- 
pany, who designed them. 

1. The small Benesh machine {Figure 3).^'^ This 
machine consists of a chamber and an atomizer built 
into one compact unit. The all glass chamber has a 
volume of 18 1. It can hold 40 mice, 7 rats, or 7 guinea 
pigs. It is built with double walls between which a 
suction of 13^ inches of water is maintained. This 
prevents leakage of toxic material. To insert animals. 


the whole chamber is raised by a rack and pinion. 
When the chamber is lowered, a gastight seal is main- 
tained by rubber gaskets. A constant air flow of 
180 1pm is maintained by a combination pump and 
meter driven by a synchronous motor. This is also 
geared to the mechanism for delivery of the toxic 
liquid, so that even if the motor should vary the same 
proportion of toxic agent to air would be maintained. 

The agent is displaced from a buret by a rising 
column of mercury. It flows through stainless-steel 
tubing to a small stainless-steel concentric atomizer. 
The mercury column is connected through a U tube, 
omitted in Figure 3, to a brass cylinder filled with 
oil. A stainless-steel piston, 0.250 inch in diameter, 
is driven into the cylinder at a known constant 
rate. This drives oil into one leg of the U tube, and 
mercury out of the other. The piston is driven by 
a lead screw, connected through a change gear box 
to the synchronous motor. Three hundred and 
eighty-five gear changes are provided. A high-speed 
motor is belted to the lead screw for rapid return of 
the piston. 

The main air stream is divided so that 158 1pm 
goes directly into the chamber while 22 1pm enters a 
compressor which feeds the atomizer. The spray 
from the atomizer enters a spiral evaporator which is 
provided with a flow of hot water of controlled tem- 
perature; the air stream of the atomizer may also be 
heated. Less volatile materials are condensed on and 
evaporated from the spiral coils. 

An inverted mercury-water U tube provides an 
estimate of the nominal concentration and a check on 
the accuracy of displacement. In use, the mercury 
level is set at the zero mark in the first leg of the 
U tube. During the run, mercury is driven into this 
bulb, displacing water, which displaces mercury from 
the next bulb into the third bulb containing the solu- 
tion to be displaced. At the end of the run the mer- 
cury in the first bulb is drained off back to the zero 
mark, and weighed. When the machine is free from 
leaks, better than 99 per cent recovery is obtained. 

The Benesh machine is used as follows. Either the 
density of the agent is determined, or a solution of 
known density and concentration is made up. From 
this is calculated the revolutions per minute needed 
to give the desired concentration. The change gears 
are then set to give the correct rpm. It is usually 
possible to select a gear setting such that the rate of 
delivery is within 2 per cent of the amount desired. 
Revolution counters on the carriage are set to give 
the number of revolutions needed for a run of the 


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APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 



desired time. The animals are placed on the chamber 
floor and the chamber lowered. The toxic agent is 
placed in the buret. The machine is placed in gear 
and started. 

The exposure does not start until the first revolu- 
tion counter is tripped. Prior to this, the agent is dis- 
pensed into the system, but exhausted before reach- 


ing the chamber. When the first revolution counter is 
tripped solenoids are actuated which turn off the ex- 
haust valve and open a stopcock to admit mercury 
into the measuring buret. The exposure continues 
until the second revolution counter is reached and 
thrown. This automatically disengages the motor and 
turns on the exhaust valve. The animals are then re- 


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METHODS OF DISPERSING AGENTS INTO CHAMBERS 


289 


moved. If a different concentration of the same agent 
is to be tested, it is only necessary to change the gear 
and revolution counter settings. It is possible to 
make as many as five 10-minute runs on the same 
solution within an hour. 

The maximum concentration that can theoreti- 
cally be attained with any substance is one-eighth of 
its equilibrium volatility at the temperature of the 
heating coils. Since the air flow through the coils is 
too rapid for saturation to take place, the actual con- 
centration obtainable is somewhat less. 

The machine should not be used with substances 
which attack mercury and stainless steel. In practice, 
materials which react slowly with mercury can be 
used. 

2. The large Benesh atomizer. The atomizer on the 
small Benesh machine was permanently connected to 
one small chamber. It could not be used with aero- 
sols, which came to form an increasingly important 
part of the work. The large Benesh machine was 
built to retain the advantages of the smaller machine 
in a somewhat more flexible form. The essential de- 
sign was retained, but the following changes were 
made. 

a. The volume of the buret containing the 
toxic liquid was increased from 25 to 130 ml. 
This permitted longer runs or higher con- 
centrations to be used. 

b. The oil-mercury system was somewhat 
cumbersome and prone to leakage. It was 
made necessary by the use of a brass cylin- 
der. Changing the size of piston used was a 
major operation. In the large machine direct 
displacement of mercury was made possible 
by the use of an all-steel system. 

Three concentric pistons, 1 inch, 3^ inch, 
and 34 inch in diameter are used. The two 
larger pistons can be quickly locked down 
and used as cylinders for the next smaller 
size. The pistons and lead screw are mounted 
vertically on a section of channel which can 
be inverted for removing air bubbles from 
the cylinder. 

The largest piston displaces mercury at 
the rate of 0.6435 ml per revolution of the 
lead screw; the other pistons displace in 
proportion to their areas. The stroke is 
about 10 inches, the maximum displacement 
about 130 ml. 

c. In place of the change-gear box on the small 
machine, three pairs of standard loose 


change gears connected by idlers are used. 
These are changed by hand, with a wrench. 
Twenty sizes of change gears are available. 
By using the several gears and pistons 
available several thousand rates of displace- 
ment are theoretically possible, ranging 
from 0.008 to 7,000 ml/min. In practice 
both extremes are avoided, because of the 
inaccuracy of the first and the high pres- 
sures produced by the second. 

The ease of changing gears in the small 
Benesh machine made it convenient to make 
up one solution and change concentrations 
by changing the rate of displacement. With 
the large Benesh atomizer it was frequently 
more convenient to leave the gears set at a 
certain ratio and make up different solu- 
tions for the desired concentrations. 

d. The atomizer, driven by a refrigerator com- 
pressor operating at 45 to 70 psi, sprays 
directly into the chamber rather than into 
a condenser. This makes it possible to use 
aerosols. Solutions of agents of low volatility, 
such as glycerine, may be used to produce 
aerosols of a size determined by the concen- 
tration of the solution. Thus 0.1 per cent 
solution gives clouds of mass median di- 
ameter [MMD] 0.3 11 and 5 per cent gives 
an MMD of 4.0 m from droplets initially 7 m- 

e. This atomizer has none of the automatic 
controls used on the small Benesh machine. 
Return of the pistons is made by a hand 
crank geared to the lead screw. 

This atomizer cannot be used with ma- 
terials with low boiling points, inasmuch as 
no provisions were made for cooling the 
storage buret. It should not be used with 
materials which react with mercury or 
stainless steel. 

3. The small, constant-flow atomizer . Many of the 
features of the Benesh atomizers can be retained in a 
very simple apparatus. 

Standard, all-glass syringes are used as pistons and 
cylinders. These are connected to a small glass con- 
centric atomizer. Connection to the atomizer may be 
made by an all-glass system, but a short piece of rub- 
ber tubing is preferred to prevent breakage. Syringes 
ranging from 1 to 100 ml may be used. They are held 
in two metal brackets by rubber collars. 

The lead screw is geared by bevel gears to a 1/150 
hp Bodine synchronous motor geared down to 


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290 


APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


3 rpm. No provisions for changing the gear ratio are 
made, and changes in concentration must be made 
by changing the syringe size and the concentration 
of solution. The machine is made to give 18 minutes 
of running, which allows for equilibration time and a 
10-minute exposure. The machine will deliver from 
0.044 to 1.74 ml/min with the various syringes. The 
piston is returned by reversing the motor and running 
the machine backwards. The syringes can be cooled 
by laying rubber bags filled with ice water across 
them. This cooling is adequate for a 75 per cent solu- 
tion of hydrogen cyanide in ethanol. This machine is 
quite satisfactory. Nominal concentrations can be 
estimated from the change in reading on the syringe. 
It can be set up on almost any chamber and used 
with almost any agent. Slightly more complex design 
would provide changeable gear ratios and a quick 
return device. 

4. Modified Sinks atomizer For work with the 
wind tunnel an atomizer was needed that would give 
an estimate of the amount of agent delivered at any 
time during a run. A commercial spray nozzle was 
modified for this purpose. The nozzle was a Binks 
#174 humidifier nozzle obtained from the Binks Mfg. 
Company of Chicago. The body of this is a bronze 
casting which contains a needle valve concentric to a 
conical air passage. An indicator arm fitted with a 
hairline was attached to the handle of the needle 
valve. A 360-degree protractor dial was fitted to the 
body of the nozzle. With these, precise and repro- 
ducible settings of the needle valve could be made. 
The fluid feed inlet was fitted with a 25-ml buret ce- 
mented into a brass sleeve threaded to fit the body of 
the valve. Compressed air at 10-25 psi was supplied 
through a corrugated hose fitting threaded into the 
lower inlet. At 15 psi and with a fluid feed of 2.0 ml/ 
min, a cloud of MMD 8.0 m was obtained. Finer 
sprays were obtained with higher air pressures and 
slower feeds. 

The principal advantage of this atomizer is the 
direct reading of the amount of solution delivered 
during a run. The output tends to vary somewhat 
with the hydrostatic head in the system. The atomizer 
cannot be used with substances which attack brass. 

Impinging Atomizers.^ In these atomizers the jet 
of spray from the atomizer strikes a baffle plate. 
Larger particles stick to the wall and run back to the 
liquid reservoir, whereas smaller ones remain air- 
borne and are swept out of the chamber, either by the 
air blast from the atomizer itself or by an auxiliary 
air supply. 


Theoretically these devices could use either a con- 
centric or a right-angle atomizing unit. To save space 
the right-angle unit is commonly used. This unit 
must be adjusted before sealing into its container. 
The size of particles obtained (and inversely the out- 
put of the atomizer) is largely determined by the 
distance of the jet from the baffle plate. The wall of 
the container may be used as a baffle, or a small plate 
may be fitted in front of the orifice. 

1. Multiple-jet impinging atomizer These im- 
pinging atomizers work at a very low efficiency. Per- 
haps 5 per cent of the output of the atomizing unit 
passes out of the nozzle as aerosol. This results in a 
quite low delivery. It was necessary to develop an 
atomizer which would set up larger amounts of ma- 
terial as an aerosol for use in the wind tunnel. Im- 
pinging atomizers of partially metal construction 
were developed. The atomizing unit consists essen- 
tially of a hollow brass tube, about an inch in diam- 
eter, with the lower end plugged and the upper end 
connected to the air line. Near the lower end #55 
holes are spaced equally around the circumference. 
A small brass tube, with the upper end machined, is 
soldered to the body of the cylinder at right angles 
to the axis of each hole. The lower end of this tube 
dips into the liquid to be dispersed; the upper end is 
centered in the jet of air from the hole. The most 
successful of the atomizers has eight of these jets. A 
shield in the form of a truncated cone is soldered 
base down around the units to form a baffle. This 
does not greatly affect particle size but it facilitates 
return of fluid to the bottom of the bowl. 

The vessel in which these are placed consists of a 
1-1 Florence flask to the neck of which is sealed a side 
arm of the same diameter. The shape and diameter of 
the side arm determines the particle size. This side 
arm is fitted with a trap which returns liquid to the 
reservoir. A bulge on the bottom of the flask provides 
for efficient scavenging of small amounts of liquid. 
The diameter of all tubing through which the aerosol 
passes is kept as large as possible. 

The eight-jet atomizer, operated with 5 cfm of air 
at 20 lb pressure delivers from 1.5 to 2.3 g/min with 
agents of low volatility. These atomizers can produce 
clouds of MMD from 2.0 to 3.5 m- 

These atomizers overcome the main drawback of 
impinging atomizers, i.e., low delivery. Impinging 
atomizers cannot be used with binary systems, as 
they fractionate them, the more volatile component 
distilling over. Impinging atomizers tend to give a 
flat and fairly linear curve for output versus 


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METHODS OF DISPERSING AGENTS INTO CHAMBERS 


291 


pressure, which makes fine adjustments in output 
practical. 

The Dispersal of Particulates 

Certain of the atomizers used above may be used 
for the dispersal of particulates, as solutions or 
molten solids, as well as for vapors. There are in addi- 
tion several methods peculiarly adapted to the dis- 
persal of particulates. 

The Dry Dusting Atomizer It became neces- 
sary to test the toxicity of dry dusts in comparison 
with that of atomized droplets of solutions. The 
“dry-duster’’ was developed for this purpose. It is 
essentially an atomizer for dispersing dry powders. 
The body of this atomizer is a straight tube, 25 mm 
in diameter. It is separable in the middle by a ground- 
glass joint, for ease in filling. A glass nipple is sealed 
to the lower end. A sintered glass disk (40-60 mesh) 
is sealed across the bottom of the lower member, just 
above the constriction. The powder is placed on this 
sintered disk. A side arm, constricted distally, is 
sealed to the upper member. A tube side of smaller 
diameter is ring-sealed through the opposite wall to 
extend concentrically into the side arm. 

In operation this device is charged with powder, 
assembled, and placed in a flexibly mounted clamp. 
A clamp attaches the assembly to an eccentric 
mounted on the shaft of a small electric motor. The 
vigorous agitation so provided tends to prevent 
channeling, and to ensure a uniform rate of disper- 
sion. The two concentric tubes sealed to the upper 
portion constitute an atomizer. The Venturi vacuum 
produced by passage of compressed air through the 
inner member draws a current of room air through 
the sintered disk. This current draws the particles up 
to the atomizer and into the chamber. Much closer 
regulation of the output is possible if instead of re- 
lying on the vacuum, a slow current (1 1pm) of dry 
nitrogen is passed through the lower inlet. 

A good estimate of the nominal concentration is 
provided by the weight loss of this duster. The ap- 
paratus disperses particles at approximately their 
original size. The shearing action of the air blast 
shatters aggregates to a certain extent. 

Fractionating Devices. As it is difficult to obtain 
clouds of a desired particle size, a fractionating de- 
vice is sometimes introduced between the atomizer 
and the exposure chamber. Two forms of fraction- 
ators have been used. 

1. Fractionating tower. This device makes use of 
the fact that the mass and volume of a particle de- 


termine its rate of settling. This relation is formu- 
lated in Stokes’ law. By passing a current of air up a 
vertically mounted tube those particles which fall at 
a velocity greater than that of the air current will 
settle out; smaller particles with slower rates of fall 
will be swept up the tube. Such a tower may be used 
to reject either small or large particles, depending on 
whether the outlet for desired particles is placed at 
the top or the bottom of the tube. 

A tower of this sort was used for work with one 
particulate to exclude all particles above 5 ^ in 
diameter. One has been used for work with another 
agent dispersed from an impinging atomizer in the 
molten state.^^^ In this tower particles below 75 y 
were sucked upward and rejected, while the larger 
particles were allowed to fall downward into a small 
wind tunnel. 

2. Rotating macro-imping er.^^^ One of the princi- 
ples widely used in analytical instruments for aero- 
sols has been that of impingement. A jet of aerosol- 
laden air is driven at high velocity against a surface. 
The larger the particle, the better its chance of 
sticking. 

An attempt was made to use this method on a 
larger scale to reduce the mass median particle di- 
ameter of a dry aerosol (see Chapter 12). This was 
done by impacting the dispersed agent at a high 
velocity against a moving kymograph drum which 
had been coated with vaseline. A moving surface was 
used for impaction to prevent overloading. The 
smaller particles which did not stick to the drum 
were passed into an exposure chamber. 

This equipment was able to reduce the MMD only 
from 6.3 to 3.8 y. It was somewhat bulky and its use 
was abandoned. However, this method of reducing 
the MMD has certain inherent possibilities. 

3. Serial macro-impingers.'^^^ Large impingers (see 
Figure 4) operated in series have been successfully 
used to reduce the MMD of a NaHCOs cloud below 
1.0 y. Filtration flasks lined with vaseline are used, 
with a central tube extending down from the top. 
The size fraction taken out is regulated by adjusting 
the position of this tube and varying the air flow. 
This method is less cumbersome and more effective 
than the rotating impinger. 

Electrical Atomization . This method of dispersal 
is peculiarly well adapted to the dispersal as aerosols 
of metals and other conductive, heat-stable materials 
which are not obtainable in a finely powdered form. 
The material to be dispersed is used as an electrode 
for a high-voltage arc. If the material is to be dis- 


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292 


APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


12 



I 

A Critical pressure orifice from compressed air line at 15 psi (de- 5 Macro-impinger (1-liter filter flask containing Vaseline and oil 

livers 38 1pm). mixture). 

B Manometer (maintained at 3 psi). 6 Macro-impinger (500-ml flask as above). 

1 Flask holding powder to be dispersed. 7 Mixing flask (2-liter). 

2 Air jet (directed to side to facilitate mixing) . 8 Manifold. 

3 Settling column (130 cm high, 5 cm in diameter). 9 Stationary fan blades of opposing rotation. 

4 Vaseline-coated impinger. 10 Cotton plug (permits escape of excess air). 

11, 12 Exits to mask and to sampler. 

Figure 4. Dry cloud apparatus. 


persed as an oxide, the arcing is carried on in an at- 
mosphere of oxygen; otherwise helium or hydrogen 
may be used. The aerosol is mixed with dry air and 
led into a small chamber; regulation of the concen- 
tration is achieved by varying the amount of diluent 
air. 

Aerosols obtained by this method are extremely 
fine, somewhat less than 0.3 m in diameter. The out- 
put of the arc is quite constant, and regulation of the 
concentration is made by regulating the air flow. 

16.4 SAMPLING EQUIPMENT 

It is usually necessary to know not only the con- 
centration of agent put up in a chamber, referred to 
as the “nominal” concentration, but also to know 
the concentration actually existing in the chamber. 
This concentration is determined by chemical or 
physical methods and referred to as the “analytical” 
concentration. With vapors, it is only necessary to 
know how much of the material is dispersed in a cer- 
tain volume of air. With particulates, in addition to 
this information, it is necessary to know something 
about the size of the individual particles. 

16.4.1 Equipment for the Sampling of 
Vapors 

Most of the apparatus for determining the concen- 
tration of vapors in gassing chambers is of common 


use in the study of air pollution. UCTL practices 
are as follows. 

1. Withdrawing of the gas sample is effected by 
either a water aspirator or an electrically driven 
pump. 

2. Measurement of the volume withdrawn is usu- 
ally made by a wet test meter. This meter is cali- 
brated by the positive displacement of a known vol- 
ume of air through it. Familiarity with methods used 
in field trials led to the use of critical pressure orifices 
for regulating sampling rates. 

3. The type of absorbing bubbler most commonly 
used in this laboratory is made of glass. A coarse 
sintered disk is used to break up the gas into bubbles. 

An investigation was made of the efficiency of 
three types of bubblers,^^' the sintered disk type,® 
the Bushnell type, which has a plain inlet tube ex- 
tending about 5 cm into the absorbing liquid, and 
the Edgewood type, which is filled with glass beads. 
The absorption of H was studied, and a Northrup 
titrimeter used to measure the slippage. The sintered 
disk type was found to be the most efficient. The fol- 
lowing conclusions governing the use of bubblers 
were drawn from this study and coincide with others 
j ndependently obtained . 

1. The absorbing solvent should have a low vapor 
pressure. 

2. If possible the solvent should react with the 
absorbate to give a nonvolatile compound. 


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SA3IPLING EQUIPMENT 


293 


3. The absorbent should dissolve water vapor if 
the air has an appreciable humidity. 

4. A solvent which foams considerably is to be 
preferred to a nonfoaming solvent, other factors be- 
ing equal. 

5. Low temperatures are conducive to better ab- 
sorption. 

6. The flow rate of the gas should be kept as low 
as possible. 

7. The kind of bubbler is of less importance than 
has usually been assumed. 

Two devices for the analysis of vapors have been 
developed at the UCTL. They are described below. 

Low-Resistance Absorber. Investigations of the 
hydrogen cyanide content of expired air (“precision” 
gassing) required a bubbler that would combine low 
resistance, small volume of absorbent, and small 
dead space with high efficiency at intermittently high 
flow rates. It was necessary to design a new type of 
bubbler to meet these specifications. 

This absorber consists essentially of a pair of con- 
centric glass tubes. The outer is 37 cm long and 
2.2 cm inside diameter. Inside, it is a tube with both 
ends closed, 33 cm long and of such a size as to leave 
a 1-mm annular space between it and the outer tube 
as an air passage. The outer tube is fitted at its ends 
with male ball joints so that it can be freely and con- 
tinuously rotated about its long axis (Figure 5). It is 



Figure 5. Low-resistance absorber. 


rotated by two micarta pulleys, 2 inches in diameter, 
bored out to fit the outer tube, and cemented to it. 
These pulleys rest on the rollers of a small ball mill 
(Fisher Minimill). The whole assembly is mounted 
on two rods attached to the sides of the ball mill. 
Two brackets hold the corresponding female ball 
joints flexibly. The absorber is held down against the 
rollers by helical springs attached to slip rings. 

In use 8 ml of absorbent are poured into the ab- 
sorber. This is more than enough to wet all exposed 
surfaces when the absorber is rotated. Thereby the 
absorbing surface is continually being renewed. Tests 
have shown resistance to be very low, about 1 cm of 
water at an air flow of 30 1pm. When 3 per cent 
NaOH in ethanol is used as an absorbent, the absorp- 
tion of hydrogen cyanide is 100 per cent from air con- 
taining 2.4 mg/1 and flowing at 7 1pm. It is 95 per 


cent when the flow rate is 30 1pm. Only 30 ml of wash 
liquid are needed, as compared to 500 ml needed for 
a bead bubbler of somewhat lower efficiency. The 
absorber and its motive power form a fairly compact 
unit. 

An Electronic Interval Timer for the Northrup Ti- 
trimeter.^- The Northrup ti trimeter is an electro- 
chemical analytical instrument® for the quantitative 
determination of the airborne concentrations of 
chemical warfare agents (see Chapter 36). A sample 
of contaminated air is drawn in at a constant rate. 
At intervals it is titrated with a dilute bromine solu- 
tion. The titration is carried on in one half of an 
Ag/AgN 03 //Br 2 /Br~ cell, with a platinum indiffer- 
ent electrode. When oxidation is complete, an excess 
of bromine creates an electrical potential, which is 
recorded on a galvanometer. The amount of bromine 
solution needed is determined by the time required 
for it to flow from a constant-head buret. 

This instrument is made in two forms. In the sim- 
pler field model the bromine solution is run in by the 
operator, who shuts off the flow when the galva- 
nometer shows a positive reading. In the automatic 
model the galvanometer mirror reflects a beam of 
light on a photocell when the titration is complete. 
The photocell actuates relays which shut off the 
buret and start another sampling period. The length 
of sampling period is controlled by fixed cams, which 
give a choice of four periodicities; from 1 minute 
sampling and 2 titrating to 50 minutes sampling and 
10 titrating. Between the end of one titration and the 
start of the next sampling period the cell is kept in 
equilibrium — the agent sampled during this period 
is balanced by intermittent addition of bromine. The 
opening and closing of the bromine buret is recorded 
by a relay-actuated marking pen writing on a paper 
record wound around a kymograph drum. 

In this form the automatic model was incapable of 
accomplishing some of the determinations that were 
desired at UCTL. In particular, the shortest time 
interval available (cycle repeated every 3 minutes) 
was too long for showing variations in concentration 
occurring at a frequency greater than that, whereas 
the provision for 1-hour sampling periods was un- 
necessary. The cyclic rate could have been increased 
by cutting another cam. However, it was desirable to 
eliminate the time lost between the end of one titra- 
tion period and the start of the next sampling period 
which results from the use of the cam timing mech- 
anism. 

An electronic method was adopted. The sampling 


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APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


time interval is governed by the time required to dis- 
charge a condenser of high capacit}" through a high 
resistance. The resistance was controlled by a po- 
tentiometer; changing this setting varied the time of 
discharge, and hence the sampling rate. The sizes of 
the elements used were such as to give continuous 
variation between 0.25 and 5.8 minutes; a longer 
sampling period proved unnecessary but use of larger 
condensers would provide it. At the end of the sam- 
pling period titration starts and continues until all 
the agent collected during the pretitration period 
plus that collected during the titration period is 
titrated. Thereupon the titration stops and essen- 
tially instantaneously a new cycle begins. 

This addition to the laboratory model Northrup 
tit rime ter has the following advantages. 

1. Continuous variation in sampling times is avail- 
able merely by turning a knob. 

2. As soon as one titration period has been com- 
pleted, a new sampling period begins. 

3. By using short time intervals the concentration 
of agent in the absorption cell is kept very low at all 
times, thus reducing the loss of material by slippage. 

4. The original instrument is now adapted for use 
in determining concentration changes in gassing 
chambers over short periods of time. 

16.4.2 Equipment for the Sampling of 
Particulates ® 

Filters. One of the simplest ways to determine the 
concentration of a smoke is to draw a measured sam- 
ple of air through an efficient filter and determine its 
gain in weight. At UCTL much early work with 
smokes was done with cotton-asbestos mats (40 per 
cent cotton — 60 per cent asbestos) 1 to 2 mm thick, 
pressed into perforated or sintered glass filtering fun- 
nels (25 mm in diameter). Suction of from 0.6 to 
2.0 inches of mercury was needed to pull 3 to 4 1pm 
through these. 

Work on certain types of aerosols (see Chapter 12) 
introduced several new requirements for a filter.^^"^ 
Since the determinations involved a micro procedure, 
it was necessary that the filter material have a low 
blank (less than 20 yug). The filter chosen should not 
be clogged by as much as 10 mg of a standard prepa- 
ration and should offer low resistance to air flow. 
Several filter papers were tried before one made from 
cellulose acetate was found to be satisfactory. This 
paper contained no material simulating the material 
determined in the analytical* procedures. Insoluble 
material could be completely floated off, and the batt 


could be completely dissolved in a suitable organic 
solvent, leaving the particles unaffected and ready 
for counting. 

In use, both in the laboratory and in the field disks 
of the paper are stamped out. They are held in brass 
holders in which they are backed with a wire screen. 

Precipitators. Particles have been removed from 
the air by direct precipitation. A Watson thermal 
precipitator has been constructed and used. In this 
instrument the air passes over a Nichrome wire kept 
at 100 C. Smokes are precipitated on cover slips 
backed by brass blocks. 

Electrostatic precipitation has also been used in a 
small Cottrel-type precipitator.^^ This is essentially a 
long glass cylinder. Copper screening is wrapped 
around the outside, and attached to one terminal of 
a 15,000-volt transformer. A wire in the tube at its 
long axis forms the other pole. 

Impinging Devices. An impinging device is one in 
which the smoke-laden air is drawn or driven at high 
velocity against a prepared surface. The particles 
may be trapped on the baffle plate or absorbed by 
some liquid medium. Impinging devices may be used 
either to collect all of the particles in one stage or to 
fractionate the particles by using jets of various 
speeds. 

1. The atomizing impingeri^^^ This unit (see Fig- 
ure 6) consists of a concentric atomizer mounted in- 



A Inlet tube. 

B Baffle (supported by rod from A. not shown). 

C Capillary. 

D Distance between capillary and baffle. 

E Exit to vacuum. 

F Fluid to be atomized. 

Figure 6. Atomizing impinger. 

side of a glass vessel in such fashion that its jet 
strikes a baffle plate and drains down to a sump from 
which it is re-atomized. Dust particles in the incom- 
ing air ring strike the baffle plate and are trapped. 

A straight tube is ring-sealed concentrically 
through the top of a side arm test tube. The inner 
tube is constricted at its inner end to give a jet. A 


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SAMPLING EQUIPMENT 


295 


smaller tube is ring-sealed through the wall of this 
inner tube in such a fashion that its outer end ex- 
tends at right angles, and its inner end is concentric 
to and extends through the constricted portion, 
forming a concentric atomizer. This outer end dips 
dowm into a bulge on the outer tube which acts as a 
sump. The apparatus is mounted horizontally. A 
glass arm supports a baffle plate w^hich is carefully 
positioned in front of the jet. If this plate is too close 
to the orifice the atomizer wdll not function; if too far 
aw^ay the unit will act as an atomizer and not as an 
impinger. A source of vacuum is attached to the side 
arm, and the inlet tube connected to the chamber. 

This pattern has proved 90 per cent efficient in the 
collection of clouds which had been allow^ed to settle 
for 30-40 minutes and contained particles wnth an 
MMD of 6 //. A practical advantage of the apparatus 
is that the collecting volume is small and, conse- 
quently, small amounts of toxic agent are not diluted 
too much for injection into animals. 

The Cascade Impactor. The construction, method 
of use, experimental results, and theoretical principles 
of the cascade impactor are fully described by K. R. 
May.^® Experiments at the UCTL have emphasized 
the desirability of the instrument with dry particles 
and have employed slightly different calculation pro- 
cedures, such as the substitution of the MMD on 
each plate for the effective drop size [EDS] used by 
Porton. With dry clouds a total sample of about 

0.350 mg represents the maximum which can be ob- 
tained without overloading if the cloud is distributed 
on all four slides. With dry powders the presence of 
aggregates in the airborne cloud complicates the 
calculation of the MMD. These aggregates fre- 
quently break up upon impaction so that they can- 
not be measured microscopically. Since the density 
of an aggregate is lower than that for unitary parti- 
cles, the aggregate is impacted along with unitary 
particles of smaller size. This property leads to the 
recommendation (Chapter 15) that particulates 
should be assessed in terms of impactibility rather 
than in terms of diameter. 

1. A device for increasing the load on cascade im- 
pactor slides The amount of a particulate impacted 
upon slides No. 3 and No. 4 of the cascade impactor 
must be kept very small to prevent overloading. The 
quantity obtained on one streak is barely within the 
limits of the available analytical methods. To allow 
collection of a larger sample, a method of moving the 
slides at intervals during sampling was devised so 
that it is now possible to obtain eight streaks on 


slide No. 4 and four streaks on slide No. 3 during one 
sampling period. A heavier cap is screwed on to the 
appropriate tubes of the cascade. In the center of this 
cap a hole is drilled and tapped for a 34 "inch bolt. 
The bolt is passed through this cap. The inner end 
bears on the slide. This bolt is turned by hand at in- 
tervals during the run to move the slide. The distance 
it is moved is determined by the number of rotations 
of the screw. 

2. A modified cascade impactor for use with small 
particulates}'^^ The cascade impactor was originally 
designed to handle the range of drop sizes set up by 
munitions in the field. In work wdth nasal filtration 
of small droplets it was necessary to work in a range 
of much smaller sizes. The larger drops in this range 
were of about the smallest size that the standard 
cascade impactor w^ould handle at 17.5 1pm. The 
standard cascade with critical orifice impinger and 
filter backing w'ould trap the particles in this range 
but would not fractionate them. 

A modified cascade was constructed which frac- 
tionated the drops which slipped past slide No. 4 and 
were caught by the impinger. The standard cascade 
has a rate of flow through its jets of 5, 30, 50, and 
80 mph, with the impinger giving 700 mph. The mod- 
ified cascade has jet velocities of 56, 86, 177, and 
700 mph, the last slit being a critical orifice. (A criti- 
cal orifice gives a speed of flow equal to the speed of 
sound — approximately 700 mph.) It will be noted 
that the first two jets of this cascade correspond, 
roughly, to the last two jets of the standard cascade, 
while the last two correspond to the impinger, as used 
with the standard instrument, and an intermediate 
value. This modified impactor has proved capable of 
efficiently fractionating a cloud which slips past the 
standard instrument. This modified instrument re- 
quires a backing filter to collect all material. 

The present experimental model is blown of glass. 
The four separate sections fit together with rubber 
stoppers. The slides are held in place between in- 
dentations in the walls. Wall losses can be easily 
detected by inspection. 

Particle Fractionators. Drop traps, chemical noses. 
In an attempt to simulate the characteristics of nasal 
passages with respect to particulates, various devices 
have been made to fractionate the cloud into a lung 
fraction and a nose fraction. 

Glass tubing in the form of Z’s and S’s such as 
were used by British workers for liquid droplets were 
coated with a sticky film of alkyd resin in an effort 
to fractionate dry particulates.^^”^® Better results 


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APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


were obtained with selectors which were essentially 
the first stage of a cascade impactor backed by a 
filter.^if 

Wires for Sampling Particulates. The use of slides, 
tubes, and wires of different dimensions for the de- 
termination of particle size and cloud concentration 
has been described in detail.^^^’*"’® 

16.5 METHODS FOR ^TRECISION 
GASSING” 

In the usual gassing procedure no account is taken 
of the effect of the toxic agent on the respiratory 
volume or rate. Consequently, there is no means of 
determining the inhaled LAo from the LC 50 . Some 
species, especially rabbits, hold their breath to agents 
which are apparently undetected by other species. 
Methods which take account of the actual respira- 
tion during exposure have been termed “precision 
gassing” methods. A tracheal cannula and Douglas 
bag were employed in studying the effects of phos- 
gene on the respiratory pattern of dogs.^^® In some 
instances the respiration was modified by the use 
of 

For the early investigations on the effects of hy- 
drogen cyanide, the animal was mounted in a body 
plethysmograph attached to a Brodie bellows. 

More precise methods were later developed 
in which a mask was fitted to the animal. A valve 
with minimal dead space was used and a special low- 
resistance absorber constructed. 

16.5.1 Equipment 

The Mask. The first mask tried was made of 
vinylite sheeting, shaped in a truncated cone. The 
apex of this was cemented to the male half of a 16/22 
standard taper joint. This was used with dogs. The 
animal’s snout was taped shut, and the cone bound 
over it so that the apex of the cone was in contact 
with the nostrils. 

When this facepiece was applied in the usual man- 
ner, an average leakage of 17.5 per cent was found. 
When it was applied very tightly, the leak was re- 
duced to an average of 4.4 per cent. In order to 
achieve this low leakage the facepiece had to be ap- 
plied with sufficient pressure to embarrass respira- 
tion seriously. 

This facepiece subsequently was replaced by a pair 
of nasal tubes beveled at one end to facilitate in- 
sertion. These tubes (IJ^ inch long, and 4 mm inside 
diameter) were attached by paragum rubber tubing 


to the diverging arms of a glass Y tube sealed onto 
the end of a 15/20 male standard taper glass joint. 
The tube ends were closely approximated to the 
Y arms so as to expose as little rubber surface as 
possible to the agent. After gassing no adsorbed agent 
could be detected on the inside of the nosepiece. 

It was possible to handle animals so intubated with 
local anesthesia alone (cocaine or butyn) but this 
was not entirely satisfactory. Therefore intubation 
was carried out on lightly anesthetized animals (for 
dogs, 20 mg/kg of Nembutal intravenously) after a 
swab of 1 per cent cocaine or butyn had been applied 
to the nostrils to prevent sneezing. The mouth was 
closed with elastic bandage and the tubes were then 
inserted and fixed with additional tape. No leakage 
could be detected in 11 of 12 animals tested, and the 
other had only 1.9 per cent leakage. 

The Valve System. The first valve used was a 
copy of the all glass valve designed by Weston and 
Tobias. The body of this valve was made from two 
female and one male 16/22 joints sealed together in 
a T. The long arm was made from a male and female 
joint, and the side arm from a female joint. In use 
the long arm is mounted vertically with the male 
joint at top. The valves proper are composed of glass 
disks ground flat, of such diameter as to fit inside the 
female joint. The end of the male joint is ground fiat 
and serves as a valve seat. The disks are held down 
in place by their own weight. The assembly of male 
joint and disk is inserted in a female joint which 
keeps the disk in line. Such a valve will pass air in 
the direction away from the male joint. 

In use, the dog’s snout is connected to the female 
joint on the side arm. The lower valve is connected 
to a gassing chamber, and the upper, through a suit- 
able absorber, to a spirometer. On inspiration the 
lower valve opens and permits contaminated air to 
enter. On expiration, the lower valve closes, and the 
upper valve opens and passes air to the absorber. 

It is desirable to minimize the dead space as much 
as possible. The use of glass imposes limits on the re- 
duction which can be made. In addition the convul- 
sions of exposed animals place great strain on the 
valve. 

It was possible to machine a valve from brass 
which would have less dead space. The valve is of the 
same general design, except that both the body of 
the valve and the flaps are made from brass. The 
valve has only 13 ml of dead space as compared to 
25 ml in the glass valve, and is practically unbreak- 
able. It was found that while untreated brass ab- 


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METHODS FOR "^PRECISION GASSING” 


sorbed appreciable quantities of cyanide, brass 
“blued” by immersion in a hot solution of AS2O3 in 
HCl did not react with cyanide. 

The Absorber. The use of an absorber to collect 
gases from air, as expired, imposes certain peculiar 
requirements. It must be efficient at intermittently 
high flows (as much as 30 1pm), it must have low re- 
sistance (conventional absorbers have a resistance of 
several inches of mercury under these conditions), 
and it must be possible to rinse it out with a small 
volume of liquid, since very small quantities of agent 
are present in the expired air. 

The first absorber used was the Edgewood low- 
resistance, glass-bead type.^^ This absorber is filled 
with fluid and drained just before use. Thus, the gas 
passes over the surface film and not through liquid. 
However about 500 ml of wash liquid was needed to 
transfer all the absorbed agent to the titration vessel. 
With the very small amounts of material present, 
this large volume of solution led to appreciable titra- 
tion error. The UCTL low-resistance absorber^^^" 
described (Section 16.4.1) proved more satisfactory. 

16.5.2 Determination of Inhalation 
Toxicity of Particulates 

As described in Chapter 15, the effect of particle 
size on physiological action is appreciable. In order 
to determine whether an inhaled particle was trapped 
in the nose or in the lung or whether it was exhaled 
again, various methods were devised similar in prin- 
ciple to those employed in “precision gassing” experi- 
ments with vapors but modified for the assessment of 
particles. 

1. One procedure for use with animals involved 
exposure to toxic clouds of controlled particle size. 
It was used with agents which are highly toxic in the 
lung but of negligible toxicity in the nose. From these 
experiments the relation of particle size to toxicity in 
mice, rats, and rabbits was determined (Chapter 15). 

2. Correlated with these experiments were meth- 
ods for the determination of toxicity by intrapul- 
monary instillation of solutions of the toxic agent.^^® 

In general the trachea of an anesthetized animal is 
cannulated, and the solution instilled into the trachea 
through a tube which fits inside the cannula. The 
method has previously been used for rats.^^ A small 
catheter is used. The neck is transilluminated with a 
Spencer microscope lamp to aid observation of the 
trachea. 

For mice this method was modified as follows. A 


297 


cannula which fits snugly into the trachea of a 20-g 
mouse is made by rounding off the beveled tip of a 
IJ^-inch 18-gauge needle. A IJ^-inch handle is at- 
tached to the hub. The solution to be instilled is con- 
tained in a -ml tuberculin syringe tipped with a 
25-gauge needle. The mouse is etherized and tied on 
its back. The mouth is held open and the tongue held 
'against the mandible with a pair of blunt forceps. 
The throat is transilluminated and the larynx is 
visible as a bright spot opening and closing with the 
respiratory movements. The cannula is inserted into 
the trachea through the larynx. When the cannula is 
situated correctly, it is possible to cause a pulsation 
of the chest by blowing gently into the cannula. The 
25-gauge needle is then inserted into the cannula, 
and the solution instilled. When in position, the tip 
of the 25-gauge needle should be flush with the tip of 
the 18-gauge cannula. If the cannula is in the right 
position, the breathing becomes labored upon in- 
sertion of the 25-gauge needle, and returns to normal 
when the needle is removed. 

16.5.3 Nasal Filtration and Lung 
Retention 2 ik,i, 27 f-i 

The mensuration of these factors involves setting 
up a particulate cloud and determining its particle 
size with cascade impactors before and after passage 
through portions of the human respiratory system. 
Obviously these tests could be done only with non- 
toxic materials. Either non hygroscopic or hydrophi- 
lic aerosols may be used ; dyed corn oil and calcium 
phosphate were used for the former, and NaHCOs 
for the latter (see Chapter 15). The basic techniques 
involved in these determinations are the same; differ- 
ences will be discussed under the subheadings. 

Setting up the Particulate Cloud. In the first work 
corn oil (Mazola) dyed with Sudan Red was sprayed 
from the large Benesh atomizer. When NaHCOs was 
used, it was dispersed from a 250-ml Erlenmeyer 
flask with a two-hole stopper. A glass tube drawn 
out to a fine tip extended through the stopper to 
near the bottom of the flask. When compressed air 
was forced through this jet, a cloud of NaHCOs dust 
emerged from a tube in the other hole of the stopper. 
This cloud was directed into a 12-1 bottle, and the 
large particles allowed to settle out for 5-10 seconds. 
The particles remaining airborne were then drawn 
into the common entrance of the Y tube. It was 
found early in the experiments that the cloud dis- 
persed as described was quite heterogeneous. Though 


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298 


APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


passing through a common tube, samples drawn si- 
multaneously from the tw^o arms of the Y tube 
showed markedly different distributions on the im- 
pactor slides. This was remedied by placing two 
small, oppositely oriented, metal propellers in the 
common tube. This stirred the passing air sufficiently 
to make the cloud uniform. 

The same setup was used for calcium phosphate 
smokes. Further fractionation was provided by the 
use of serial macro-impingers, lined with Vaseline 
(see Figure 4). 

1. Dry cloud apparatus. The dry cloud of NaHCOa 
was set up by the apparatus shown in Figure 4. Fif- 
teen pounds pressure in excess of atmospheric applied 
to a critical pressure orifice for 18 1pm (at atmos- 
pheric pressure) gives a flow of about 38 1pm, suffi- 
cient to supply the lung and the control without di- 
lution by unfiltered room air. The material enters the 
settling column. The agitation here is adequate to 
maintain the cloud at nearly the same concentration. 

The pressure in the manometer was about 3 psi, 
practically all of it being due to impinger No. 6. The 
jet in impinger No. 4 was simply a large glass tube. 
In No. 5, the end of the tube was somewhat flattened, 
whereas in No. 6 the orifice in the end of the tube 
was about 1x5 mm. For smaller clouds a still smaller 
jet may be used, the pressure in the column being 
larger. To maintain the same flow rate only a slight 
shift in the initial pressure is required. If one starts 
with considerably higher initial pressures with a 
proportionately smaller orifice in No. 1, changes in 
pressure in the column may be ignored. 

Between runs the impingers were warmed to re- 
surface the bottoms of the flasks and the mixing 
flask 7 and tube 8 were blown clean. At the end of a 
run the last flask should not be too heavily coated. 

Passage of the Cloud through a Portion of the Human 
Respiratory System. The experiments conducted were : 

1. Nasal filtration with corn oil. The oil was 
sprayed from the Benesh atomizer into the 700-1 
chamber. This was operated at a flow of 300 1pm and 
acted as a settling chamber. A glass Y tube, 22 mm 
in diameter, led from the chamber. One branch of 
this Y led to a mask which fitted tightly over the nose 
and mouth of the subject. This mask was from a com- 
mercial dust respirator; an inflatable rubber tube 
formed a tight gasket with the subject’s face. Pro- 
truding into the mask was a second exit tube 
about which the subject closed his mouth. The 
exit tube led through a cascade impactor, backed 
by an impinger, to the pump. The second branch 


of the Y tube led to another impactor, also backed 
by an impinger and the pump. This impactor sam- 
pled the incoming cloud. The tubing between it 
and the fork of the Y tube was comparable in 
length and shape to the tubing which led to and 
from the mask. As far as could be controlled, the only 
difference between the two air streams was that one 
passed through the subject’s nose and the other did 
not. The impingers backing the impactors were of 
such size as to be critical orifices, with a flow of 
17 1pm. Each experiment was done in duplicate with 
the positions of the control cascade with its corre- 
sponding impinger, and the mask exit cascade with 
its impinger, reversed during the second experiment. 
This canceled out instrumental errors. 

Sealed to the mask exit tube and preceding the 
cascade impactor was a small glass tube through 
which air could be drawn from or added to the sys- 
tem. This could be used to increase or decrease flow 
rate through the mask while maintaining the same 
flow through the cascade impactor. A similar tube 
preceded the control cascade. A second small opening 
in the tube which connected the mask to the cascade 
impactor led to a manometer which indicated the 
reduction in pressure caused by the resistance of the 
nose when air was flowing through it. 

During each experiment, which lasted 30 seconds, 
the subject held his breath so that there was no ap- 
preciable passage of the aerosol into and out of his 
lungs. For the flow rate of 10 1pm, the 30-second run 
was repeated immediately in order to obtain a larger 
sample. The nasal resistance was found to be very 
low except in individuals whose nasal passages were 
congested or who were not sufficiently relaxed during 
the experiment. If a person is tense, his posterior 
nares may become constricted, with a marked in- 
crease in resistance. Subjects were used in the experi- 
ments only after they had had sufficient practice on 
the apparatus to allow a 10 1pm flow with a resistance 
of 0.3 inch water, 17 1pm with 0.5 inch, and 29 1pm 
with 1.0 inch or less. In the case of some subjects this 
low resistance could often be achieved only after in- 
halation of benzedrine, or the nasal instillation of 
neosynephrine solution. 

2. Nasal filtration with NaHCOs particles. Com- 
mercial powdered NaHCOs was chosen as a nonirri- 
tating, nonaggregating powder containing particles 
of a size range from 1 to 15 (microns). The same 
assembly of mask, Y tube, impactors, critical pres- 
sure impingers, and pump was used as with the corn 
oil work. The impactor slides were covered with 


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METHODS FOR TESTING VESICANTS 


299 


alkyd resin, and the NaHCOs on them analyzed 
electrometrically. 

The hygroscopic! ty of NaHCOs introduced several 
difficulties because of the moisture picked up by 
passage through the nose. It was necessary to oven- 
warm the impactor before use, and to warm the cloud 
from the nose by passing it through an 8-inch length 
of 15-mm tubing, electrically heated to give an 
emergent air stream of approximately 90 C. A dupli- 
cate heating device was used in the control air stream. 
The wetting and subsequent drying of the cloud 
passing through the nose compacted and rounded 
the particles in it. It was necessary to humidify the 
control cloud also. The humidifier was a metal tube 
(1 foot long, 1 inch inside diameter) lined with a 
water-soaked blotter, placed in a thermostated water 
bath. This humidifier was also an inefficient im- 
pactor, taking out about 20 per cent of the airborne 
material in the cloud going through it. A similar tube, 
lined with Vaseline, had to be placed in the path of 
the cloud to be transmitted through the nose. After 
these modifications quantitative agreement between 
the NaHCOs contents of the dry and humidified 
cloud could be obtained. With the use of cellulose 
acetate filters instead of the cascade impactors it was 
unnecessary to have the various driers. 

3. Retention of particles in human lungs. In these 
experiments the subject’s nose was plugged. Stop- 
cocks were placed in each of the two sampling tubes 
between the critical orifice and the filter. 

During an experiment the subject inhaled for a 
fixed period, the beginning and end of which were in- 
dicated to him by an operator. During the inhalation 
period a sample of the incident cloud was drawn 
through filter A, by opening the corresponding stop- 
cock (the vacuum pump operated continuously). 
During exhalation, which was also for a fixed number 
of seconds, the exhaled cloud was drawn through 
filter B. The cycle was repeated 10-15 times, depend- 
ing on the length of inhalation and exhalation periods. 

Since the incident and exhaled clouds were sampled 
at the same rate and for equal periods, the material 
found in the exhaled cloud represented the unre- 
tained fraction of an inhaled quantity equal to that 
on the other filter. 

The total volume breathed during an experiment 
was governed by the rate of withdrawal of the ex- 
haled cloud from the mouth. The volume withdrawn 
during each period was considered to be the tidal air. 
The exhaled tidal air was, of course, constant from 
period to period since it was controlled by the sam- 


pling instrument. The inhaled tidal air, however, 
varied from period to period depending on whether 
or not the subject inhaled a volume which exactly 
compensated for the amount withdrawn during the 
previous exhalation. Over a number of cycles, of 
course, the average volume inhaled had to be equal 
to the volume exhaled. 

This method has been studied with smokes of 
NaHCOa and calcium phosphate. Since calcium 
phosphate is nonhydroscopic it is possible to dis- 
pense with the humidifying and drying sections of 
the apparatus. 

16.6 METHODS FOR TESTING VESICANTS 

The usual method for testing the vesicancy of an 
agent is to put a known amount of it on the skin of 
the forearm and to observe the results at a later time. 
The agent may be put on as either a liquid or a vapor; 
it may be either still or flowing. 

16.6.1 Testing Vesicants as Liquids 

The Edgewood Rods.^’^^ One of the simplest meth- 
ods for testing compounds for vesicant action in- 
volves the use of a series of stainless-steel rods of 
standard weight with tips varying from 0.6 to 2.68 
mm in diameter.^^ With the exception of the smallest 
rod, all of them deliver 0.022 to 0.029 mg of H per 
square millimeter. These rods, usually known as 
“Edgewood rods,” are touched to the surface of a 
pad saturated with the vesicant and then applied to 
the skin. Liquids were used either undiluted or dis- 
solved in diphenyl ether. Solids were also dissolved 
in diphenyl ether. 

The method is simple and although all the material 
on the surface of the rod is not delivered to the skin, 
easily reproducible burns result from the use of a 
given rod with a given compound. In general the 
rods have not proved satisfactory for comparison of 
vesicants since a separate calibration is required for 
each compound tested. It is not possible to test oint- 
ments with these rods, since the droplet cannot satis- 
factorily be delivered to the surface of ointment- 
covered skin without breaking the covering. Further, 
the method is not desirable for compounds that react 
with steel, although it has been used with lewisite. 
Nonstandard sets of glass rods have also been made. 

“Drod.” It was necessary to devise some form of 
micropipet which would deliver small, known vol- 
umes of vesicant. Trevan used a standard microm- 
eter caliper to drive a 1-cc syringe. A modification - 


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APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


called the Drod used a specially constructed microm- 
eter head to drive the plunger of a tuberculin 
syringe. A spring click bears on 12 longitudinal 
grooves on the barrel of the head, each click corre- 
sponding to 30 degrees of rotation and the delivery of 
about 0.2 cu mm of liquid. (The amount would be 
constant for each syringe, but commercial syringes 
are not interchangeable, being individually ground 
to fit. The diameters of the pistons, and hence the 
volume delivered, vary between syringes.) A 27- 
gauge needle, with the tip ground flat and square, is 
used to deliver the liquid. 

The instrument is sturdy and portable. It delivers 
an accurately measured small dose, which is not so 
dependent on the physical properties of the agent as 
is the case with the Edgewood rods. This apparatus 
requires considerable time to fill, and the change 
from one vesicant to the other requires decontamina- 
tion of the syringe and tip, making it unsuitable for 
use when many different liquids are to be handled in 
one day. The amount of liquid delivered per click is 
large, with the result that dilutions must frequently 
be used. 

The Modified Drod? An attempt was made to 
modify the original Drod to make it more suitable. 
Several modifications were made on the driving head. 
It was redivided, so that a click occurred for each 
7.5 degrees of revolution (48 clicks per revolution). 
The instrument then delivered 0.065 mg of H per 
click, instead of the original 0.2 mg. A 6-inch indi- 
cator disk, with 192 divisions, and a pointer arm at- 
tached to the head made it possible to split the clicks 
in half, and possibly into four. These are equivalent 
to 0.032 mg and 0.016 mg of mustard. 

The 3^^-cc tuberculin syringe was retained. It is 
filled with mercury, which is used to expel the agent 
from a removable delivery tip. The syringe and screw 
are attached by a ground joint to a three-way stop- 
cock. With the stopcock in one position, the agent in 
the tip may be expelled by turning the micrometer. 
With the stopcock in the other position, the tip may 
be filled or washed by liquid which enters from a side 
arm. A platinum or graphite surfaced stopcock is 
used to avoid fouling the agent. 

It is possible with this modification to remove one 
vesicant, decontaminate the apparatus, and load an- 
other vesicant in less than 1 minute. It was found 
that dividing the clicks into four did not give repro- 
ducible lesions, but 0.032 mg of mustard, correspond- 
ing to half clicks, can be delivered quite accurately. 
This amount, although small, was not small enough 


for some purposes. The increments were too coarse 
to discriminate between vesicants of nearly similar 
potencies. 

Other Pipets. Capillary tubes have been used for 
the application of measured amounts of vesicant.^^ 
The capillaries were however rather fragile and the 
method is not adapted to testing large numbers of 
men. A device for blowing drops of measured size off 
a microburet tip was developed at Porton.^^-^^ 

The Benesh Micropipet}^ In the Drod type of 
micrometer syringe the piston was of a diameter 
equal to the bore of the cylinder. To achieve a smaller 
displacement with the same pitch lead screw, it was 
necessary to reduce both bore and piston diameters. 
The 3"^-cc syringe already in use was the smallest 
available size. Micropipets capable of delivering 
smaller quantities of liquid have previously been de- 
scribed.^^ Various features in their design were not, 
however, suited to vesicant testing. 

The Benesh micropipet was based on a some- 
what different displacement principle. The piston 
was a steel wire 0.0122 inch in diameter. This entered 
a mercury chamber through a Neoprene gasket. The 
volume of mercury displaced was equal to the volume 
of wire which entered the chamber, but since the 
piston worked by displacement it was unnecessary 
for it to be tightly fitted to a cylinder. This scheme 
avoided the difficulties of accurately machining such 
a small size hole. The wire piston is driven by a 
micrometer head, somewhat larger than usual, but of 
standard design. Twenty-five grooves are cut on the 
thimble actuating a spring click. The lead screw has 
the standard micrometer pitch of 40 threads to the 
inch. The dimensions of the wire and the pitch of the 
lead screw are such that each click (l/25th revolu- 
tion) advances 0.002 cu mm (2.5 gamma) of H. 

The mercury chamber communicates with a re- 
movable tip, made out of capillary tubing. The end 
of the tip is optically polished. The instrument is 
mounted to move up and down on a rod screwed to 
a wooden base. The base forms the bottom of the 
carrying case, with the rod serving as a tie rod to 
hold the top and bottom of the case together. The 
instrument can be transported as easily as a com- 
pound microscope. 

The apparatus is durable and simple. It has been 
found to give reproducible lesions. The principal de- 
fect is incomplete delivery of all the material ad- 
vanced to the capillary tip. It is necessary that each 
subject’s arm come in contact with the tip with the 
same pressure. The extent of loss due to the evapora- 


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METHODS FOR TESTING VESICANTS 


301 


tion of the compound between the time it gets to the 
tip and the time that it is applied to the subject is 
unknown. It is minimized by maintaining a regular, 
rapid rate of application. The instrument can best be 
used by a trained pair of operators, one operating 
the micropipet, the other holding the men’s arms 
against the tip. A regular rhythm soon leads to both 
speed and accuracy. 

It was found that the necessity for counting a 
number of clicks repeatedly led to personal error. 
An attachment was made for the pipet that made 
it possible to advance the desired amount in a single 
motion, rather than by counting a number of clicks. 
A brass plate with 25 holes equally spaced around 
the periphery was attached to the instrument. An 
index arm was attached by a ratchet to the lead 
screw. By placing taper pins in the appropriate holes 
any number up to 25 clicks can be delivered without 
counting. 

Liquid Vesicant Cup}^'^ Occasion arose to compare 
the action of HNS as a liquid with saturated HNS 
vapor. The vapor concentrations were set up in vapor 
cups (see Section 16.6.2). The apparatus employed 
for the application of liquid consisted of a small cup, 
12 mm outside diameter and 8 mm inside diameter, 
with two capillaries leading from it. One capillary 
leading directly upwards from the cup, was attached 
to a safety flask and a charcoal column aspirator; the 
other tube, coming from near the base of the cup at 
a 45-degree angle, is connected with a three-way 
stopcock. A pear-shaped bulb with a small hole in 
the side is sealed to the vertical arm of this stopcock. 

The liquid vesicant is placed within the bulb, and 
the stopcock is turned so that the vertical arm is con- 
nected with the cup. The cup is placed on the sub- 
ject’s arm, and the vesicant is drawn by suction out 
of the bulb, through the capillary, and into the cup 
until the area on the arm is covered with a continu- 
ous layer of vesicant. At the end of the exposure 
period 5 per cent hydrochloric acid is sucked through 
the instrument, followed by water; by applying the 
suction intermittently, the surface of the arm is 
flushed and decontaminated. In control tests with 
fat-soluble dyes all visible dye was removed within 
5 seconds. 

16.6.2 Testing Vesicants as Vapors 

For proper evaluation of the vesicancy of a com- 
pound the vapor hazard must also be determined. 

Edgewood Vapor Cups}^ One of the simplest ways 
of producing vapor burns is by the use of small glass 


cups with a flat rim. A pad of filter paper or some 
other absorbent material is placed in the bottom and 
moistened with the liquid vesicant. The cups are 
then taped on to the arm of the subject for the de- 
sired length of time. 

The amount of vapor (and its effectiveness) in the 
cups will vary as a result of the interplay of outside 
temperature, skin temperature, amount of moisture 
under the cup, and the presence or absence of sun- 
light on it. The actual concentration in the cup is un- 
determinable and may be changed by cooling or 
warming the cups. In addition to vapor burns, “rim 
burns” sometimes occur. These are the result of con- 
densation of liquid agent on the lip of the cup. The 
use of these cups permits the application of approxi- 
mately saturated concentrations of vapor. 

Modified cups have been devised which permitted 
the application of subsaturation concentrations, pro- 
vided for circulation of the vapor, and eliminated 
rim burns. 

The Vapor TrainV Some of the objections raised 
to the use of the Edgewood cups are similar to those 
raised against the use of “static” chambers. A dy- 
namic method of exposure was devised to overcome 
some of these difficulties. 

This apparatus consists of the following essential 
parts. (1) A bubbler from which the agent is vaporized. 

(2) A second bubbler in which water is vaporized. 

(3) A Y tube that unites the streams of vapor-laden 
air from the two bubblers. (4) Glass tubing which is 
branched and rebranched to divide the vapor-air 
stream into four identical streams. This tubing, 
20 mm inside diameter, is in several sections that are 
joined by 29/42 standard taper joints. (5) Four appli- 
cator orifices. Each may be described as an open cup 
with a delivery tube for conducting the vapor-laden 
air to it and a side arm that serves as an outlet. The 
cup is formed from a 24/40 male standard taper 
joint. The delivery tube, 8 mm inside diameter, enters 
the cup at the bottom through a ring seal and pro- 
trudes to within 3 mm of the upper, open end. The 
vapor-air stream, therefore, flows upward through 
the delivery tube, impinges upon the skin of the arm 
which a subject holds over the opening of the cup, 
and out through a side arm. The velocity of this jet 
is about 5 mph. (6) Four stainless-steel adapters for 
the applicators, each with an 8-mm hole in the cen- 
ter. Use of these adapters reduces the area of skin 
exposed and thus minimizes the severity of the re- 
sultant lesion. Each cap has a small ridge at its outer 
edge (1/32-inch deep) to prevent an arm from mov- 


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302 


APPARATUS AND TECHNIQUES IN TOXICOLOGICAL STUDIES 


ing around during exposure. The caps are held in 
place by rubber bands. (7) A branched and rebranched 
glass tube, identical with (4) but used for uniting the 
effluent streams from the applicators. (8) A tube to 
conduct the combined effluent into a suitably venti- 
lated duct. (9) A sampling apparatus to draw a meas- 
ured volume of the effluent through a suitable ab- 
sorber for determination of the analytical concentra- 
tion of the vapor (see above). (10) Platforms upon 
which subjects rest their arms while holding them 
over the applicators. These are small tables of ap- 
propriate height with holes through which the appli- 
cators protrude about 34 inch. The skin is thus held 
firmly against the cap of the applicator without an}^ 
possibility of excessive pressure, and the arm rests 
comfortably during the exposure. 

This apparatus, with a volume of 2 1 and an air 
flow of 20 1pm, can be classified as a small, high-flow 
chamber. Concentrations of agent can be used up to 
saturation; the humidity of the air can be varied 
from dryness to saturation. Good analytical-nominal 
ratios are obtained. The apparatus is rapid and con- 
venient to use. 

Use of Dyfiamic Chambers for Body Exposures. 
Almost all of the standard type chambers in this lab- 
oratory have, at one time or another, been equipped 
for body exposures. The bodies of the animals are 
exposed to contaminated air, while their heads are in 
fresh air. A gasket around their necks prevents leak- 
age of the noxious air and its inhalation. In one of 
the earliest methods ^ for use with a small smoke 
chamber the animals were placed in the chamber and 
provided with a manifold through which pure air 
circulated. It has been more common practice to 


place the bodies of the animals in the chamber and 
let their heads protrude. The first chamber to have 
built-in provisions for body exposures was the 200-1 
chamber.® 

Use of Wind Tunnel for Testing Vesicants on Man.^^'^ 
The wind tunnel (p. 285) is equipped with ports 
through which arms can be inserted perpendicular 
to the air stream. Since turbulent flow occurs, it was 
necessary to expose an annular space around the 
arm. 

The arm was prepared for exposure by wrapping 
the hand and wrist to a point 5 cm above the distal 
end of the ulna with oilcloth sealed with adhesive 
tape. A piece of adhesive tape 2 inches wide was 
placed around the forearm leaving an exposed an- 
nulus of skin 1 cm wide between the wrist covering 
and the adhesive tape. Another piece of oilcloth cov- 
ered the remainder of the forearm and elbow, leaving 
a second (proximal) annulus between the 2-inch tape 
and the elbow covering. To deliver two doses to the 
same arm the distal (wrist) annulus was left exposed 
for the whole exposure period; the proximal (elbow) 
annulus was kept covered with oilcloth except for the 
appropriate terminal fraction of the exposure period. 
At the end of the exposure the coverings were re- 
moved and discarded. 

The use of the wind tunnel permits testing the 
relative efficiencies of aerosols and vapors at various 
wind speeds. Temperature and humidity of the air 
stream can be controlled only by controlling the 
temperature and humidity of the laboratory. 

The Great Lakes Man-Chamber.'^^ This apparatus 
for testing effects of vesicant vapor on masked men 
has been described in Section 16.2.2. 


SECRET 


Chapter 17 


PHYSIOLOGICAL MECHANISMS CONCERNED IN THE PRODUCTION 
OF CASUALTIES BY EXPOSURE TO HEAT 


By Alan R. Moritz 


17.1 INTRODUCTION 

A t a meeting called at the instigation of the 
Technical Division of the Chemical Warfare 
Service on March 22, 1944, certain deficiencies in the 
existing state of knowledge concerning the casualty- 
producing effectiveness of the flame thrower were 
discussed. Attention was called to the fact that, al- 
though both heat and the inhalation of irrespirable 
or poisonous gases probably contribute in varying 
degrees to these effects, little was known regarding 
their relative importance. 

It was recommended that the physiological section 
of Division 9 of the National Defense Research Com- 
mittee [NDRC] investigate the various mechan- 
isms by which flame thrower action may cause dis- 
ability and death. In this chapter are reviewed the 
studies that were made of the mechanisms by which 
excessive environmental heat may lead to early dis- 
ability and death. 

17.2 PILOT EXPERIMENTS TO EXPLORE 
CASUALTY-PRODUCING ATTRIBUTES 
OF GASOLINE CONFLAGRATIONS 

A certain amount of general information concern- 
ing the thermal and chemical attributes of gasoline 
conflagrations was prerequisite to the planning of an 
experimental program. For the purpose of orienta- 
tion, certain exploratory investigations were made 
of the rate, magnitude, and duration of the changes 
that occur in the temperature as well as of those that 
occur in the atmospheric concentrations of oxygen, 
carbon dioxide, and carbon monoxide incident to the 
burning of measured quantities of flame thrower fuel 
in both closed and ventilated spaces. 

17.2.1 Experimental Procedure 

A series of experiments ^ were accordingly under- 
taken in which gasoline was burned in a fireproof 


room having a capacity of 14.4 cu m. The construc- 
tion of the room was such that it could be either 
closed or ventilated at will. The fuel was poured into 
shallow metal pans which completely covered the 
floor, which measured 1.6x3 m. Approximately 4 li- 
ters were burned during each conflagration. 

To measure the changes in temperature, 40 gauge 
iron-constantan spot-welded thermocouples were 
suspended in the center of the chamber. The thermo- 
electric potentials provided by the thermocouples 
were amplified by means of an electronic optical 
bridge circuit.^® It was found that the use of a split 
circuit is capable of amplifying a 1-mv input poten- 
tiometrically to a 5-ma output in less than 0.2 sec- 
ond. Since this amplifier was a null-point instru- 
ment, it was independent of all the electronic tube 
characteristics, of the intensity of the light beam 
focused on the photocell, and of the input resistance 
of the thermocouple leads. Two such amplifiers were 
constructed. 

Two recorders were used. One was an Esterline- 
Angus recording milliampere meter (5 mil, full scale) 
with a response time of 0.5 second. The other was a 
General Electric photoelectronic recording milli- 
ampere meter with a response' time of 0.2 second. 
Both recorders had 12 inch per minute chart drives. 

By means of a selector switch the sensitivities of 
the amplifiers were usually set so that a 40-mv input 
produced full-scale deflections of the recording pen. 

Method of obtaining samples of atmosphere for 
gas analysis: Three long tubes, each having an in- 
ternal diameter of 2 mm, extended from the outside 
to the center of the conflagration chamber. These 
tubes passed through the wall at the bottom, middle, 
and top of the room. Samples of 300 ml were with- 
drawn as desired by attaching evacuated flasks with 
ground joints to the ends of these tubes. The gas 
samples obtained in this manner were analyzed for 
O 2 , CO 2 , and CO by means of a standard Orsat ap- 
paratus. 


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303 


304 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


17.2.2 Temperatures Developed during 
Gasoline Conflagrations 
Unventilated conflagrations: In these experiments 
the door was kept closed during the fire. Oxygen de- 
pletion resulted in extinction of the conflagration in 
about 30 seconds after ignition. Approximately half 
of the gasoline contained in each pan remained un- 
burned. When the door was opened following the 
premature extinction of the fire, the room was found 
to be filled with dense black smoke and there was a 
strong odor of gasoline'. 


A 



B 



Figure 1. Continuous temperature recording during 
burning of gasoline in rectangular (6x10x10 ft) combus- 
tion chamber. 

(A) No ventilation. Two thermocouples, one 5 ft 
and the other 3 ft above floor level. Distance from floor 
to ceiling was 10 ft. 

(B) Room ventilated for 50 seconds. One thermo- 
couple 5 ft above floor. 

Figure lA shows continuous temperature records 
provided by the two thermocouples, one of which 
was hung midway between the floor and ceiling in 
the center of the 3 m high conflagration chamber, and 
the other approximately 0.9 m above the floor. 

Because of rapid convection currents, the upper 
thermocouple reached higher temperatures than did 


the lower. The sharp peaks in the temperature curve 
of the upper thermocouple are also due to convection 
currents. The average temperatures recorded by the 
two thermocouples over a 30-second period were ap- 
proximately the same, namely, about 500 C. At the 
termination of the combustion, the ambient temper- 
atures fell rapidly and uniformly. The curves shown 
in Figure lA are typical of all experiments in which 
the conflagration was unventilated. 

Ventilated conflagrations: Figure IB shows a con- 
tinuous temperature recording of a thermocouple 
which was situated about 1.5 m above the floor dur- 
ing a conflagration in which ventilation sufficient to 
maintain complete combustion was provided. 

The temperatures obtained were about the same 
as those recorded during un ventilated conflagrations. 
The duration of the high-temperature plateau de- 
pended on the length of time that the door was left 
open. In the experiment in which the record shown 
in Figure IB was made, the door was left open for 
50 seconds. 

17.2.3 Extrapolation of Experimental 
Temperature Changes to Conditions Likely 

to Prevail in Bunkers and Pillboxes 
Incident to Flame Thrower Attack 

It was judged that the circumstances which pre- 
vailed in the experiments just described probably 
predisposed to the development of maximal temper- 
ature elevations. It is regarded as unlikely that 
higher temperatures would be developed in bunkers 
or pillboxes incident to flame thrower attacks in 
which gasoline was used as fuel. Due allowance 
should be made for the tolerance of commercial re- 
cording instruments in the interpretation of data 
pertaining to temperature changes in bunkers and 
pillboxes incident to field tests of the effectiveness of 
flame thrower equipment. Thermocouples of the 
usual size and potentiometers or millivolt meters of 
the usual period are not capable of following the 
rapid temperature fluctuations that occur in un- 
ventilated or incompletely ventilated gasoline con- 
flagrations. Furthermore, temperature observations 
made by such apparatus may be lower than the 
actual temperatures obtained by as much as 500 C. 

17.2.4 Exposures of Animals to Burning 

Gasoline 

Adult dogs (6-8 kg) and young pigs (7-12 kg) 
were exposed in various ways to burning gasoline. 


SECRET 


ATTRIBUTES OF GASOLINE CONFLAGRATIONS 


305 


Table 1. Effects of temperature and combustion products resulting from gasoline conflagrations on animals. 


Ref. 

Conflagration 

Site of 

thermal exposure 

Inhalation of 
combustion 
products 

Comp. (%) of air 
immediately 
after fire 

Fate of animal 

Blood 
after 
expt 
CO sat 
% 

Time 

sec 

Avg 

Temp 

C 

Body 

and 

face 

Body 

only 

Face 

only 

Dead 
in 15 
min 

Survival 
for hours 
or days 

With 

fire 

After 

fire 

O 2 

CO 2 

CO 

1 

30 

320 

+ 



+ 

5 min 

14.6 

4.0 

0.8 


4- 

30 

2 

40 

600 

+ 



+ 

No 

16.2 

4.0 

0.8 

+ 


7 

3 

30 

400 


+ 


No 

No 





*+ 


4 

30 

370 


+ 


No 

No 





+ 


5 

75 

700 


+ 


No 

No 




+ 



6 

30 

350 




No 

5 min 

14.7 

4.6 

1.0 


+ 

6 

7 

30 

350 



’+ 

+ 

4 min 

15.7 

3.5 

0.3 


+ 

Trace 

8 

30 

450 



-h 

+ 

4 min 

16.1 

3.6 

0.7 


+ 

37 

9 

30 

500 



+ 

+ 

2 min 



■ 


+ 

32 


The animals were anesthetized by the intraperitoneal 
injection of sodium pentobarbital and fastened by 
asbestos tape to an iron frame situated in the center 
of the conflagration room 54 inches above the floor. 
The principal data pertaining to these experiments 
are included in Table 1. 

Combined Cutaneous and Respiratory Exposure 

Animals 1 and 2 were exposed to the full effects 
(cutaneous and respiratory) of the burning gasoline. s 
Throughout the entire exposure of animal 1, the door 
of the conflagration chamber remained closed. The 
fire burned out in about 30 seconds because of in- 
sufficient oxygen. The average temperature of the 
air surrounding the animal during this period was 
320 C. The animal was allowed to breath the at- 
mosphere of the unventilated room for 5 minutes 
after the fire was extinguished. 

Samples of the atmosphere were taken for gas 
analyses as soon as the fire had burned out. The 
mean concentration of CO in the atmosphere was 
0.8 per cent, and the oxygen concentration was 
14.6 per cent. The CO saturation of a sample of the 
animal’s blood taken 5 minutes later was 30 per cent. 
Although there was no indication that the fire had 
resulted in a dangerously low oxygen or a danger- 
ously high CO 2 concentration, it did appear likely 
that the animal would have died of CO poisoning if 
it had remained much longer in the unventilated 
room. 

Although animal 1 had been severely burned, it 
did not develop early shock, required several post- 
exposure injections of Nembutal to keep it quiet, and 
was beginning to become restless with returning con- 
sciousness when sacrificed 6 hours later. Its air pas- 
sages contained an excessive amount of mucus but 


there was neither clinical nor pathological evidence 
of significant thermal or chemical injury of the 
larynx, air passages, or lungs. 

In the case of animal 2, the door remained open 
during the first 40 seconds of the conflagration, with 
the result that a larger amount of gasoline burned 
and a higher temperature was achieved and was main- 
tained for a longer period of time than was the case 
in the first experiment. At the end of 40 seconds, the 
door was closed with the result that the fire was ex- 
tinguished very soon thereafter. Samples of the at- 
mosphere were then taken for gas analyses and the 
animal removed. This dog was moribund when re- 
moved to the open air. In view of the fact that the 
atmospheric concentration of CO was similar to that 
observed in the preceding experiment, it was sur- 
prising to find that the CO saturation of the blood 
was only 7.0 per cent. The explanation of this dis- 
parity probably lies in the fact that animal 1 breathed 
the atmosphere of the conflagration chamber for a 
total of 6-7 minutes, whereas animal 2 was moribund 
at the end of 2 minutes. 

Two factors may have contributed to the ex- 
tremely rapid death of dog 2. One is systemic hyper- 
thermia caused by overheating of the blood as it cir- 
culated through the extensive superficial network of 
subcutaneous vessels. The other is respiratory ob- 
struction due to pharyngeal edema. That a signifi- 
cant degree of hyperthermia had occurred was indi- 
cated by the finding of a rectal temperature of 41.2 C 
when the animal was autopsied 5 hours after the ex- 
posure. That obstruction to respiration may have 
contributed was indicated by the presence of severe 
burning of the mouth and pharynx with what ap- 
peared to be obstructive edema of the latter. The 
trachea and bronchi contained abundant mucus 


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306 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


mixed with carbon particles. The lungs were hy- 
peremic. 

The results of the first two exposures dealing with 
the effects on animals of burning gasoline indicated 
that even in circumstances considered to be particu- 
larly favorable to the production of CO and to the 
exhaustion of oxygen, the concentration of these 
gases was not sufficiently altered to cause uncon- 
sciousness or death within 5-6 minutes. Although the 
results of the two experiments were not construed as 
proof that neither fatal anoxia nor fatal CO poisoning 
could result from a gasoline fire, they did indicate 
that such an exposure can cause rapid death from 
thermal injury alone. 

Cutaneous Exposure 

The next three experiments shown in Table 1 were 
undertaken to ascertain the effect of protecting the 
respiratory tract against heat and combustion prod- 
ucts during the time that the body was being ex- 
posed. To investigate this question, animals 3, 4, 
and 5 wore tight-fitting asbestos-covered rubber 
masks through which a continuous stream of un- 
heated air was circulated during their exposure to 
heat. The first two animals of this series (3 and 4) 
were exposed to an un ventilated conflagration of 
about 30 seconds duration and average atmospheric 
temperatures of 400 and 370 C, respectively. Al- 
though both animals showed extensive burning of the 
skin, they survived the immediate effects of heat and 
were in reasonably good condition when killed 6 
hours later. In the case of animal 5, the door of the 
room was left open for the first minute of the fire and 
for 65 seconds the temperature of the room was in ex- 
cess of 400 C. Within 15 seconds after the door was 
closed the fire went out and the animal was removed. 
This animal died immediately on reaching the open 
air and showed severe burning of all the body surface 
except where the skin had been protected by the 
mask. 

These experiments provided evidence that a rela- 
tively brief (75 seconds) exposure of the skin to a 
sufficiently high temperature could cause almost im- 
mediate death independently of other factors. 

Respiratory Exposure 

The last four experiments shown in Table 1 were 
undertaken in an attempt to investigate further the 
effects on animals produced by the breathing of the 
combustion products of a gasoline conflagration. In 
each experiment the door was kept closed throughout 


the entire conflagration. By this procedure postcon- 
flagration mixing of outside air with the combustion 
products was reduced to a minimum. The skin of the 
body was protected against excessive overheating by 
enclosing the animals to the neck in a heavy asbestos 
sack. With the exception of No. 6 the animals were 
free to breath the burning gases and hot air during 
the fire as well as the smoke which remained in the 
chamber after the fire. Dog No. 6 breathed outside 
air circulated through the mask during the fire; as 
soon as the temperature in the room had dropped to 
200 C the mask was detached by remote control and 
for the next 5 minutes only the hot smoke and air of 
the combustion chamber were available for respira- 
tion. 

None of these four animals showed either clinical 
or pathological evidence of thermal injury of the air 
passages or lungs. Two of them (6 and 7) may have 
held their breath throughout most or all the exposure 
period. That animals No. 7 and 8 breathed during 
some of the time that they were in the combustion 
chamber is indicated by their carboxy hemoglobin 
concentrations of 37 and 32 per cent, respectively. 
It is possible, of course, that even these two animals 
held their breath during the conflagration and ac- 
quired their carbon monoxide by breathing during 
the interval between the time that the fire went out 
and the time that they were removed from the 
chamber. 

17.2.5 Summary 

The ignition within a simulated pillbox or bunker 
of a well-spread layer of gasoline leads within 10 sec- 
onds to a temperature rise of between 800 and 
1000 C. The duration of such a conflagration and the 
temperature increase caused by it varied according 
to the oxygen supply and the fuel. In a closed room 
having a capacity of 14.4 cu m and measuring 1.6x 
3x3 m, the fire was extinguished within 20 seconds 
and considerably less than 250 ml of gasoline was 
consumed for each cubic meter of air space. For ap- 
proximately 10 seconds of the burning time the tem- 
perature fluctuated between 500 and 900 C. If such 
a room is ventilated, the initial temperature rise is 
similar to that which occurs in a closed room, but the 
fire continues to burn until the fuel is exhausted, re- 
sulting in a temperature fluctuation of between 500 
and 1000 C. In both instances, convection currents 
established by the conflagration resulted in marked 
fluctuations in the temperature at any given place 
within the room. During the period of rapid com- 


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BASIC CHARACTERISTICS OF HEAT AND HEAT TRANSFER 


307 


bustion the temperatures were highest near the ceil- 
ing and lowest near the floor. 

In none of the experiments conducted in this par- 
ticular type of conflagration chamber did the oxygen 
content drop below 14 per cent. The carbon dioxide 
level did not rise higher than 5 per cent nor the carbon 
monoxide level above 1 per cent. 

The most important information gained from these 
exploratory experiments was the observation that 
animals as large as dogs and pigs when exposed to 
this kind of a conflagration for more than 30 seconds 
may receive injuries that are almost immediately 
fatal. Such fatalities were not necessarily contributed 
to by asphyxia, carbon monoxide poisoning, or in- 
halation of flame. It appeared that the rapid death 
may result from systemic disturbances caused by the 
impact of heat energy on the surface of the body. It 
was obviously in order to conduct additional and 
better controlled experiments to investigate the 
physiological mechanisms concerned in the produc- 
tion of casualties through the thermal effects of 
flame thrower attack. 

17.3 BASIC CHARACTERISTICS OF 
HEAT AND HEAT TRANSFER" 

It could be inferred from the results of the pilot 
experiments reported in the preceding section that 
heat independently of other factors was an impor- 
tant, if not the most important, casualty-producing 
attribute of flame thrower action. This being the 
case, consideration should be given to the nature of 
heat and to the factors which determine the transfer 
of heat from one medium to another and from one 
place to another within the same medium. 

17.3.1 Theoretical Considerations 
The Nature of Heat 

The concept of temperature rises from the sensa- 
tions of hotness and coldness. Experience has shown 
that when two or more substances of different tem- 
perature are kept free of all outside disturbances, the 
hotter bodies will get colder and the colder bodies 
hotter; and that ultimately these substances will 
reach a state of complete thermal equilibrium (identi- 
cal temperature). The hotter bodies are said to have 
lost heat, and the colder bodies are said to have 
gained heat. This concept of heat becomes quantita- 
tive by defining a unit of heat, the calorie, as the 

® By F. C. Henriques, Jr. 


amount of heat gained by a 1 g of liquid water under 
atmospheric pressure when the temperature increases 
from 14.5 C to 15.5 C. 

This gain in heat, which is discernible through a 
rise in temperature, is associated with an increase in 
the intra- and intermolecular motion. Thus heat can 
be considered as the energy stored in a substance by 
virtue of the state of its molecular motion. Certain 
manifestations of this increase in energy are readily 
observable, for example, melting, vaporization, de- 
composition, alteration in rate of diffusion and in 
chemical reaction. 

Beside the definition of a calorie, there are other 
physical concepts pertaining to heat which are 
requisite to an understanding of the general problem 
of thermal injury. 

Heat Capacity 

Heat capacity or specific heat of a substance is the 
amount of heat which is required to raise the tem- 
perature of the substance 1 C. 

The importance of heat capacity (Cp) in thermal 
injury is readily seen by considering the respective 
injury propensity of 1 g of water (Cp = 1. 00) and 1 g 
of silver (Cp = 0.06) both at 100 C placed in contact 
with 1 g of thermally insulated skin (Cp 0.7) at 
35 C. After equilibrium is reached in the former case, 
the temperature of the skin is increased to 73 C, 
whereas in the latter case it is increased only to 
42 C. 

It is apparent that, if the skin were to equilibrate 
rapidly enough when placed in contact with a hot 
body, there is insufficient heat in 1 g of silver at 
100 C to produce injury to 1 g of skin. Actually, of 
course, the skin, because of its thermal insulating 
properties, does not equilibrate rapidly enough and 
the portion of skin nearest the silver does reach a 
sufficiently high temperature to produce injury be- 
fore thermal equilibrium is reached. Hence another 
physical property of importance is heat transfer. 

Heat Transfer 

In the experiments to be described heat was trans- 
ported to the skin by three mechanisms: namely, 
convection, radiation, and conduction. In the case of 
convection and radiation, heat reaches the skin under 
such circumstances that the heat uptake is primarily 
determined by the heat source. In the case of con- 
duction, the amount of heat absorbed by the skin is 
primarily determined by the properties of the heat 
absorber, namely, the skin itself. 


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308 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


Convection 

Convection is the mechanism by which hot air 
transports heat to a cooler surface because of the 
eddying currents that arise. The air velocities of the 
eddy currents are about 1.6 km per hour. An equa- 
tion has been developed for the transfer of ambient 
heat by natural convection from a large envelope of 
hot air surrounding cylindrical objects about 30 cm 
in diameter. 29 -35 Xhis equation shows that q, the 
caloric uptake per minute per square centimeter of 
surface, can be expressed as follows: 

q = 0.0026(Ta - (1) 

where Ta is the air temperature in C and Ts is the 
surface temperature in C. 

Thus, with a skin temperature of 40 C, air at 
100 C and 400 C will transport to the skin about 
0.4 and 4 cal/cm^/min. It is also apparent that as 
this heat is absorbed by the skin the surface temper- 
ature of the skin will rise and the caloric uptake of 
the animal will decrease with time. 

It is of interest to compare with this the caloric 
uptake rate of skin at 40 C when an atmosphere of 
steam maintained at 100 C is substituted for the air. 
Under these conditions, about 300 cal/cm^/min 
would be absorbed by the skin if the surface tem- 
perature could be maintained at 40 C. This 800-fold 
increase in caloric bombardment as compared with 
that produced by air is due to the latent heat of con- 
densation of steam. This, of course, is why steam is 
an enormously greater hazard than hot air in the 
production of heat injury. 

Radiation 

All substances give off heat in the form of radiant 
energy in amounts that are predetermined by the 
surface temperature of the substance. When this 
radiation impinges upon another body, a certain 
fraction is absorbed and changed into heat. Thus, if 
two substances at different temperatures are placed 
in an enclosure, there is a continual exchange of 
energy, the hotter body radiating more energy than 
it absorbs and the colder body absorbing more heat 
than it radiates. 

In the special case of an animal completely en- 
closed in a large box of source temperature Tr, the 
caloric uptake rate q of the animal, due to this inter- 
change of radiant energy between the skin and the 
wall of the box, is expressed by the following equa- 
tion. ^9’®® 

q = sef[_{Tr + 273)^ - (T, + 273)^] (2) 


where s is the radiation constant and is equal to 
8.2 X 10~“ calorie, per square centimeter per 
per minute, e is the effective emissivity of the hot 
walls of the box, and / is the absorptivity of the skin 
to radiation emitted at Tr. Under experimental con- 
ditions to be described, the product ef can be taken 
as about 0.8. Thus, when the skin temperature is 
40 C, the hot walls at 100 C or 400 C will radiate to 
the skin about 0.7 or 13 cal/cm^/min, respectively. 

Conduction 

Conduction is defined as the transfer of heat from 
the hotter portion of a substance to a colder portion 
of the same substance, or from a hot body in physical 
contact with a cold body, where in each case there is 
no appreciable displacement of any of the molecules 
comprising these substances. It is the latter restric- 
tion that differentiates conduction from convection. 

In certain experiments to be described heat was 
conducted from either a hot solid or a hot liquid to 
the skin. In these experiments, the purpose of both 
the solid and liquid heat source was to maintain the 
temperature of the skin surface at a predetermined 
constant value and hence the conduction of heat 
through the heat source need not be considered. In 
the hot air experiments, thermal conduction through 
air is small as compared with convection, and this 
small contribution is included in equation (1). Thus 
it is only necessary to consider conduction of heat 
through the skin. 

In all cases of heat flow by conduction, a temper- 
ature gradient must exist within the substance. If 
this temperature gradient varies with time, the rate 
of heat flow will also vary with time. The type of 
heat flow where temperature is a function of both 
position within the body and time is called heat con- 
duction in the unsteady state. Heat conduction in 
the steady state refers to all cases where the temper- 
ature at any point within a substance does not de- 
pend upon time. Under these conditions the amount 
of heat flow through the medium is determined by 
this temperature gradient and the ability of the 
body to conduct heat (thermal conductivity). The 
latter case will be considered first. The equation for 
steady-state heat conduction inside a rectangular 
homogeneous body is based upon Fourier’s law^’^^ 
and is as follows: 

9 = I (r. - To) (3) 

where K, the thermal conductivity, is expressed in 


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BASIC CHARACTERISTICS OF HEAT AND HEAT TRANSFER 


309 


calories per minute, per square centimeter perpen- 
dicular to the direction of heat flow per unit temper- 
ature gradient in C per centimeter length of path. 
L is the path length through which the heat flows 
and Ts and To are the temperatures in C at the be- 
ginning and end of the path, respectively ; q has been 
previously described. 

This equation permits the experimental determina- 
tion of the in vitro thermal conductivity of the four 
respective sections of tissue, namely epidermis, der- 
mis, fat, and muscle, and also of any combination 
thereof. 

General Theory of Heat Flow through Skin 

By making use of the preceding brief definitions of 
the various physical factors involved in the transport 
of heat to and through the skin it is possible to con- 
sider how the application of heat affects the time- 
temperature relationship within a given skin site. It 
is apparent that in order to make heat flow inward 
from the skin surface it is necessary to raise the tem- 
perature of the skin surface to an extent that over- 
comes the normal existing gradients. This can be ac- 
complished by means of an external source of heat 
through conduction, convection, or radiation. Once 
the skin surface temperature is sufficiently high, the 
heat will start to flow inward, resulting in a general 
rise in temperature within the skin site. 

This initial heat flow inward (and thus the rate of 
temperature rise within) will depend primarily upon 
two physical factors: namely (1) the heat capacity of 
the skin or the ability of the skin to absorb the heat, 
and (2) the thermal conductivity of the skin or the 
ability of the skin to transport the heat. After a cer- 
tain interval of time the amount of heat entering the 
skin site will be balanced by the amount of heat 
leaving the skin site, and the skin will be ‘^heat- 
saturated.’’ In this state the new temperature dis- 
tribution within the skin site will become invariant 
with time and the amount of heat flowing through 
the skin will depend only upon (2) and the skin sur- 
face temperature. 

It is to be recognized that this picture involves not 
only the solution of the steady state of heat conduc- 
tion but also the solution of the initial unsteady state 
of heat flow. In order to solve even the “idealized” 
picture, it would be necessary to know the initial 
temperature gradients within the tissue, the thick- 
nesses, densities, thermal conductivities, and heat 
capacities of the various layers, and the skin surface 
temperature as a function of time. 


The solution of such a problem involves the follow- 
ing Fourier heat equation 

K /(TTA_dT.t 
pC^l\ dx^ ) dt ^ ^ 

where T^t is the temperature time, t, at a dis- 
tance, X, within the skin measured from the skin 
surface, p is density, and the remaining symbols 
have been previously defined. 

The solution of equation (4) subject to these con- 
ditions is exceedingly complicated. Yet superim- 
posed upon this are the numerous indeterminate in 
vivo factors which arise when we go from the idealized 
picture to the living animal. It is useful to enumerate 
the most important of these various indeterminate 
factors. 

1. Site variations in the respective thickness of 
epidermis, corium, fat, and muscle. 

2. Variation of existing temperature gradients 
within the skin with respect to time and/or position 
of site. 

3. Unknown average rate of blood flow through 
the various skin layers, and the unknown variations 
of the unknown rate of flow with respect to position 
of site and temperatures within the site. 

4. The appearance of edema fluid in variable 
quantities which brings forth indeterminate altera- 
tion in the density, heat capacity, thickness, and 
thermal conductivity of the various layers of skin so 
affected. 

It is obvious from this discussion that any general 
solution of the time-temperature relationship within 
a skin site, when heat is applied, is not possible. How- 
ever, with certain of the experiments to be described 
later in detail, it is possible to derive to a first ap- 
proximation the time-temperature relationship in 
the layer of basal epidermal cells. These experiments 
were either (a) so conducted to bring immediately to, 
and maintain the skin surface at, a predetermined 
temperature level until the threshold of irreversible 
epidermal injury was reached, or (b) the entire ani- 
mal was completely surrounded by an envelope of 
ambient and radiant heat. These experimental con- 
ditions at the boundary of the skin surface and source 
of heat are expressed by the following equation: 

q = H{T - T,) (5) 

where q and Ts have been previously defined (see 
Section 17.3.1 under “Convection”). T is the temper- 
ature of the heat source in C and H, in cal/cm^/min, 
is known as the heat transfer coefficient. Conditions 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


under experiments (a) were tantamount to an infinite 
heat transfer coefficient {H = oo); with experi- 
ments (b), the heat transfer coefficient is finite and 
the numerical value readily obtained by combining 
the radiant and ambient contributions to heat trans- 
fer coefficient as computed by equations (1) and (2), 
respectively. In order to solve equation (4) under the 
boundary condition expressed by equation (5), it is 
necessary to assume that the ratio of the total tissue 
thickness to the epidermal thickness (approximately 
80 iu) is infinite rather than finite. This assumption 
will lead to slightly longer time intervals for ‘‘heat 
saturation” of the epidermis than are to be experi- 
mentally expected. The integration ® of equation (4) 
under the above conditions results in equation (6) . 


T. - 
T 








where 


e{Y) 




dx 


(6) 


(Ga) 


and 7 is computed by means of equation (6b). 


_ L 

“ 2l/Z (6b) 

\ pC, 


T t is the temperature of the basal epidermal cells 
at the time t in seconds. Ts is the temperature of the 
heat source. To is the temperature of the skin surface 
previous to the exposure to heat. L is the distance of 
the basal cells from the skin surface, p is the density 
of the basal epidermal layer. The other symbols have • 
been previously defined and are experimentally de- 
terminable. The integral that defines 6{Y) (equa- 
tion 6a) is respectively equal to ^ty/2 and zero when 
Y is infinite (t = 0) and Y is zero {t = oo ) . For other 
values of F, the numerical value of the integral is 
tabulated. 

The time-temperature relationships at the basal 
epidermal layer during an exposure of the animal to 
a source of constant ambient and radiant heat are 
evaluated by means of these equations in Sec- 
tion 17.3.2 (see also Section 17.9.2 under “Measure- 
ment of Heat Transfer”). 

In the experiments in which the skin surface was 
brought immediately to and maintained at a pre- 
determined constant temperature, H, the heat trans- 


fer coefficient, is nearly infinite, and equation (6) 
reduces to 



where, as before, d is given by equation (6a). It is to 
be noted that in this case Tg can be taken as the skin 
surface temperature during the entire heat exposure, 
since the temperature of the heat source is identical 
with the surface temperature once heat exposure 
begins. 

It is to be noted that equation (6c) results in a 
basal layer temperature which becomes, after a cer- 
tain time interval, essentiall.y identical with the skin 
surface temperature. Actually, a small but finite 
temperature gradient will always exist between the 
surface and the basal cell layer. This steady-state 
gradient can be experimentally determined by means 
of equation (3), and the true temperature of the basal 
layer can be quite accurately computed for any 
time t by using equation (6c) until the steady- state 
temperature obtained through equation (3) is 
reached. Computations using equation (6c) to ascer- 
tain basal epidermal temperature are given in Sec- 
tion 17.3.2, and the experimental justification for 
this theory will be considered in Section 17.6.5 (see 
also 17.6.6). 

17.3.2 An Experimental Investigation 
of Quantities Involved in Both Steady 
and Unsteady State of Heat Con- 
duction through Skin 

It is apparent that certain types of special appa- 
ratus were necessary for the evaluation and assess- 
ment of the various physical factors involved in the 
time-temperature relationship to thermal injury. 
The description of these apparatuses will now follow 
in detail. 

Heat Capacity Apparatus 

The apparatus used for the determination of the 
heat capacity of the various skin layers need not be 
described in detail since these specific he ds were de- 
termined by the well-known method of mixtures.^® 
Briefly, this procedure consists of heating a known 
weight (about 10 g) of tissue in a brass container to 
100 C and rapidly dropping it into a water calorim- 
eter. The heat capacity of the tissue was readily 
computed from the temperature rise of the water as 
measured with a Beckmann thermometer. 


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BASIC CHARACTERISTICS OF HEAT AND HEAT TRANSFER 


311 


Automatic Energy Recording Applicator 

In order to measure the rate at which heat energy 
was taken up by the skin during the entire exposure 
period at any predetermined skin surface tempera- 
ture, the following apparatus was constructed to 
simulate an infinite source of heat at any given 
temperature. 

The effect of bringing the skin in contact with a 
source of heat having infinite capacity and constant 
temperature is shown schematically in Figure 2. The 
temperature of the surface of the skin immediately 
reaches and is maintained at the temperature of the 
heat source. The rate of caloric uptake by the skin at 
the time of the initial contact is essentially infinite 
and as the skin approaches its new state of temper- 
ature equilibrium the rate of energy transfer dimin- 
ishes and finally reaches a nearly constant value. 
Thus the curve representing rate of energy transfer 
is similar to that shown in Figure 2. 


HEAT SOURCE 

Infinite Heot Capacity 
Infinite Thermal Conductivity 
Source Temperoture 
Ts 

HEAT FLUX 



Figure 2. Diagrammatic representation of rate of 
caloric uptake of skin from heat source at constant tem- 
perature, of infinite thermal conductivity and of in- 
finite heat capacity. 

The steady state of caloric uptake is a measure of 
the thermal conductance of the skin. The unsteady 
state is a measure of the ratio of the thermal capacity 
to the thermal conductivity of the skin. 

Unless the animal were completely enclosed by an 
infinite source of heat, there would be considerable 
lateral spread of energy from the application area 
(see Figure 2). It was apparent, however, that be- 
cause of lateral spread the skin in the center of the 
application area would, under certain conditions. 


gain as much heat from the surrounding area as it 
would lose to it. Thus the caloric uptake from the 
central area of the source (Figure 2) would be a meas- 
ure of the perpendicular flow of energy through the 
directly subjacent skin if a sufficiently large sur- 
rounding area were in contact with the same or a 
similar source of energy. 

A scale drawing of the caloric applicator is shown 
in Figure 3A. It consisted primarily of three separate 
parts — a cro\\Ti, a brim, and an applicator disk. The 
crown and brim were brass, whereas the applicator 
disk was copper. The three units were maintained at 
the same constant temperature by independent elec- 
trical heating units. The temperature of the crown 
and brim were controlled manually by means of Gen- 
eral Radio Variac transformers. The purpose of the 
crown was to prevent any leakage of heat from the 
applicator disk except via the exposed face. The 
brim compensated for the lateral spread of the heat 
from the surface of skin directly underneath the ap- 
plicator. The applicator was heated by means of an 
auxiliary electronic apparatus which automatically 
recorded the wattage required for continuous main- 
tenance of the face of the applicator at a specified 
temperature T. The temperatures of the crown, brim, 
and disk were measured by means of three calibrated 
10-mil iron-constantan Fiberglas duplex (Leeds & 
Northrup) thermocouple wires. The wire heating 
units were of single, silk-insulated No. 40 manganin 
wire (negligible temperature coefficient of resistance) . 
This wire was held in the indicated spiral grooves 
with a thin coat of glyptal. Copper lead wires were 
soldered to the ends of the manganin and the joints 
were electrically insulated from the metal parts with 
fine glass bushings. The electrical resistances of the 
brim, crown, and applicator were 390, 277, and 
71.75 ohms respectively. 

Three fine phonograph needles rigidly located the 
applicator disk inside the crown. The disk was held 
firmly against the needles by a rubber bushing under 
compression. A steel spring, the tension of which 
could be regulated by a hard rubber screw, controlled 
the pressure of the applicator against the skin. This 
pressure could be set between 5 and 50 g/cm^. 
Guides served to keep the numerous lead and ther- 
mocouple wires apart, so that the pressure regulation 
was reproducible. The two lead wires to the heating 
unit of the applicator were held fast against the sides 
of the Fiberglas thermocouple wire by wrapping 
with thread for the fir^t 10 cm and then with scotch 
tape. 




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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 



Figure 3 A. Cross section of automatic energy re- 
corder applicator. 

A Aplicator disk (copper). 

]i Brim (brass). 

C Crown (brass) . 

D Fiber washer. 

E Heater lead wires. 

F Heater wires (3-mil single silk manganin;. 

G Fine phonograph needles (three). 

H Brass spider for holding needles. 

I Stainless steel screw. 

J Hard rubber dowel. 

K Fiber handle. 

L Iron-constantan Fiberglas duplex thermocouple wire. 

M Threaded hard rubber cup (for adjusting spring pressure). 

N Rubber collar (for holding applicator disk tight against needles.) 

O Brass cup for rubber collar. 

P Thin stainless steel tube. 

Q Steel spring. 

The electronic apparatus which controlled and 
measured the wattage necessary to maintain the face 
of the applicator at a constant temperature T is 
shown schematically in Figure 3B. 

The basic principle of the circuit was phase con- 
trol of the four-element (GE FG95) thyratron tube.‘‘® 
In order to obtain sufficient filtered power at the 
moment that the applicator first touched the skin, it 
was necessary to operate the plate circuit with the 
220- V alternating current that was available from a 
commercial power line. The grid circuit operated on 
220-v alternating current from a radio transformer. 
This transformer was connected to produce a 440-v 
potential between point A and point B. When no 
light was striking the photocell there was nearly a 
180-degree phase difference between the grid and 



Figure 3B. Diagram of electronic apparatus that con- 
trols and measures wattage input into disk of automatic 
energy recording applicator. 


plate potential ; thus, when the plate was positive the 
grid was always sufficiently negative to prevent the 
thyratron tube from firing. When light struck the 
photocell, the resistance of this part of the grid cir- 
cuit decreased sufficiently to alter the phase rela- 
tionship of the grid and plate circuit and the grid 
was not sufficiently negative to prevent the tube 
from firing during a portion of the cycle when the 
plate was positive. Once the tube fired, the grid lost 
control (gas-filled tube) and the tube conducted dur- 
ing the remainder of the positive plate cycle. 

When the plate became negative, the plate cur- 
rent became zero and the grid again gained control of 
the thyratron. Thus the amount of current which 
flowed during the positive plate cycle depended upon 
the phase angle between the grid and plate voltage. 
This phase relationship was a function of the re- 
sistance of the photocell, which in turn depended 
upon the amount of light striking the photocell. 
Hence, the amount of light striking the photocell 


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BASIC CHARACTERISTICS OF HEAT AND HEAT TRANSFER 


313 


gave a continuously variable control of the power 
output of the plate circuit. The 50-megohm re- 
sistance shunting the photocell added stabilization 
to the circuit. The 250-/xjuf variable condenser 
‘‘tuned” the phase angle of the grid circuit to the 
best operating conditions. These conditions were 
that a 4-mm deflection of the light beam reflected 
from the galvanometer would give full control of the 
plate wattage. 

The purpose of the capacities and chokes in the 
plate circuit was to filter the pulsating thyratron 
output into steady direct current. The values of the 
condensers and chokes were necessarily large be- 
cause of the high current requirements of the appli- 
cator heater. Oscillograph tests showed no appre- 
ciable ripple current in the filtered output. The wat- 
tage or caloric input rate into the applicator heater 
was measured with an appropriately shunted Ester- 
line- Angus recording milliammeter (5 mil, full scale 
and ^ to 12 inch per minute chart drive). Six scales 
were provided by a selector switch with full-scale 
deflections of 1, 2, 5, 10, 20, and 50 cal/min/cm^ of 
applicator surface area respectively. The highest 
value corresponded to a filtered output of 36-v across 
the applicator heater terminals. 

Operation. In use the galvanometer zero was set 
to provide sufficient illumination on the photocell to 
generate about 1 cal/min inside the applicator. 

The potentiometer was now set to the predeter- 
mined millivoltage (temperature). By turning off 
and on the low-sensitivity shunt button of the type K 
potentiometer the photocell was kept fully illumi- 
nated until the galvanometer started to deflect in the 
opposite direction. The high-sensitivity button was 
now locked down and the instrument was on auto- 
matic control. Thus, if the temperature of the appli- 
cator face as measured by the applicator thermo- 
couple tended to get either hotter or colder, the gal- 
vanometer mirror moved in a direction that either 
decreased or increased the illumination on the photo- 
cell, which in turn either decreased or increased the 
wattage through the applicator. Thus by means of 
the thermocouple in the face of the applicator the 
output of the thyratron tube was thermally “locked” 
to a predetermined temperature of the applicator 
face. 

The sensitivity of the galvanometer was set to give 
a deflection of 4 mm for an 0.1 C change in tempera- 
ture. This deflection was sufficient to produce the 
maximum available power of 50 cal/cmVniin. This 
was the maximum sensitivity that could be obtained 


without producing periodic heating and cooling of 
the applicator face (slow oscillations of the recorder 
tracings of caloric uptake rate) . These oscillations in 
the power output were due to the short but finite 
time for the heat generated in the heater wire to 
affect the thermocouple. 

The heat losses of the applicator disk under the 
conditions of usage were determined by placing the 
disk and brim on a “perfect” insulator. The perfect 
insulator consisted of a flat-bottomed, thin glass cone 
which was silvered on the inside, pumped out to 
10“’ mm of mercury while being heated to 450 C for 
8 hours, and then sealed off. All heat losses from the 
inside surface of the glass were prevented by the 
bright silver surface (no radiant loss) and the vacuum 
(no molecular heat conduction). Lateral heat loss 
through the glass was prevented by maintaining the 
brim at the same temperature as the applicator disk. 

Heat losses from the applicator disk were deter- 
mined at two temperatures, namely 45 and 60 C. 
The results are given in Table 2. 


Table 2 


Exp 

Crown 

Temperature C 
Brim 

Disk 

Applicator 
disk heat loss in 
cal/cm^/min 

a 

45 

45 

45 

0.020 

b 

45 

Not heated 

45 

0.45 

c 

60 

60 

60 

0.035 

d 

61 

60 

60 

0.000 

e 

59 

60 

60 

0.080 

f 

60 

Not heated 

60 

1.1 


These data showed that when all three units were 
heated to the same temperature the heat loss of the 
disk was trivial as compared with the caloric uptake 
of the skin at similar temperatures (see Table 5). 
The slow rate of heat transfer from the crown to the 
applicator disk was indicated by comparison of ex- 
periments c, d, and e. These data showed that the 
exact setting of the crown temperature was not criti- 
cal. A comparison of the data a, h, c, and / showed 
the importance of the brim in preventing lateral 
heat leakage from the applicator disk. 

Needle Thermocouple for Determining Tissue 
Temperature beneath Sites of Cutaneous 
Exposure 

It was desirable to be able to measure the temper- 
ature of the tissue at various distances beneath the 
surface of the skin before, during, and after exposure 
to heat. For this purpose a needle thermocouple was 


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314 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


constructed by threading a single silk-insulated 
3-mil constantan wire through 4 feet of a No. 27 
gauge trochar. The bimetallic junction was then 
made by honing down the end of the trochar and 
wire to a 45-degree angle; this removed the silk in- 
sulation from the constantan wire and permitted it 
to be surface soldered to the steel hypodermic needle. 
Through experimentation it was found possible to 
insert laterally a No. 22 gauge trochar along the 
natural cleavage plane of the dermis-fat interface, 
until a point directly underneath the surface area 
to be exposed was reached. Then the No. 27 gauge 
thermocouple needle was inserted into the No. 22 
gauge trochar until skin resistance could be per- 
ceived, and the No. 27 gauge couple was withdrawn 
about 1 cm. After the heat exposure was terminated, 
the skin was cut to the needle depth and the distance 
from the muscle-corium interface to the skin surface 
was ascertained with a depth gauge. This depth be- 
fore the application of heat was ascertained by a con- 
trol experiment on a neighboring site. 

The thermal emf of the steel-constantan couple 
was read on a Leeds & Northrup Type K2 potentiom- 
eter and high-sensitivity galvanometer. The steel- 
constantan emf seemed to be very reproducible in 
this temperature range 0 to 80 C. It was about 30 per 
cent lower than the iron-constantan emf. Tempera- 
ture differences of 0.1 C were readily determined. 

Thermocouple for Measuring Surface 
Temperature of Skin 

The surface temperature of skin exposed to air de- 
pends upon two factors, namely, the rate at which 
heat reaches the skin surface from the underlying 
tissue and the rate at which the skin surface loses 
heat to the atmosphere. When the surface tempera- 
ture of the skin reaches a steady state, these two 
rates must be identical. 

The use of the usual insulated thermocouples 
for the measurement of skin temperature necessarily 
alters these conditions. Upon first applying an in- 
sulated thermocouple, no matter how perfect the 
insulation, the temperature measured will be con- 
siderably lower than the true surface temperature 
because of the relatively high heat capacity of the 
insulator. When a steady state of temperature is 
finally reached (in some cases a matter of hours), the 
temperature recorded by the insulated couple must 
be greater than the true skin temperature, since the 
skin site is no longer losing heat directly to the air. 
Thus an accurate measurement of surface tempera- 


ture by any apparatus similar to that just described 
would be fortuitous. 

A thermocouple for measuring the surface temper- 
ature of the skin in this investigation consisted of a 
bare 2 mil iron-constantan junction. The 2-mil wires 
were prepared by dissolving (by nitric acid) the ends 
of 15-mil iron and constantan thermocouple wires 
(Leeds & Northrup) for a distance of 5 mm. The re- 
duced ends of the two wires were then soldered end 
to end and stretched tightly by means of a bow made 
of brass tubing (see Figure 4). The heat capacity of 
the junction was trivial as compared with that of 
the skin. 

BRASS 



Figure 4. Thermocouple for measuring skin surface 
temperature. 


In use the junction was placed on the skin for 
lateral contact and after 10 seconds a reading was 
made. The couple was then completely surrounded 
by skin by pinching the neighboring epidermis and a 
second reading was taken within 5 seconds. Numer- 
ous such pairs of readings were recorded and in no case 
has there been any significant difference between the 
temperature of lateral and that of circumferential 
contact. Thus a bare fine wire rapidly reaches skin 
temperature (10 seconds) when it is in contact with 
the skin.*^ 

The sensitivity of an iron-constantan thermo- 
couple is such that with a Leeds & Northrup Type K2 
potentiometer and high-sensitivity galvanometer 

^ A theoretical objection to the unprotected or bare wire 
junction has been that it is partially exposed to the air and 
thus will reach a temperature somewhere intermediate between 
the air and the skin temperature. It should be kept in mind 
that the skin is also exposed to air. At normal air tempera- 
tures, the heat transfer coefficient for both wire and skin to 
air is quite small. Since the heat capacity of a fine wire is 
small and its thermal conductivity high, one would expect the 
wire rapidly to attain true skin temperature. 


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BASIC CHARACTERISTICS OF HEAT AND HEAT TRANSFER 


315 


temperature differences of 0.05 C were readily meas- 
ured. 

Determination of Heat Capacity of Four 
Pertinent Tissues {in vitro ) 

The heat capacity of pig epidermis, dermis, fat, 
and muscle were determined on approximately 10-g 
samples of each tissue by the procedure given in 
Section 17.3.2 under “Heat Capacity Apparatus.” 
Determinations were made on each tissue of two 
10-kg pigs. In order to obtain pure epidermis for 
these determinations the following method was used. 
After the hair was shaved as closely as possible, the 
pig was immersed in water at 55 C for about 1 min- 
ute, then removed, and the skin was carefully dried. 
It was then possible to remove strips of pure epi- 
dermis by scraping with a knife. The remaining tis- 
sues were readily obtained in a relatively pure state 
by dissection. 

The values of the heat capacities of these tissues 
are given in Table 3. 


Table 3. Heat capacity of pig tissue in calories per 
gram per C. 



Epidermis 

Dermis 

Fat 

Muscle 

Heat capacity 

0.887 

0.845 

0.785 

0.753 

0.538 

0.573 

0.890 

0.926 

Average value 

0.86 

0.77 

0.55 

0.91 


In view of the similar heat capacities of dry tissue, 
the above variations of the different tissues are prob- 
ably due to water content of tissue. In this respect 
the high value for pig epidermis (0.86) is understand- 
able since it was found experimentally that the water 
content, in spite of the presence of the cornified layer, 
averaged about 76 per cent. 

Determination of Thermal Conductivities of 
Tissues {in vitro ) 

The experimental determinations of thermal con- 
ductivities of pig epidermis, corium, fat, and muscle, 
were based on equation (3) of Section 17.3.1. The 
respective tissues were placed on a copper cylinder 
2 inches in diameter and 4 inches high. The auto- 
matic energy recording applicator was now placed 
over and in contact with the tissue. Thus when the 
tissue became “heat-saturated,” the knowledge of the 
caloric input into the tissue, the temperatures of the 
tissue-applicator (approximately 48 C) and tissue- 
cylinder (approximately 30 C) interfaces, and the 
thickness of the tissue permitted the computation of 


the thermal conductivity. The temperature of the 
tissue-cylinder interface was measured by means of 
an iron-constantan thermocouple soldered into the 
face of the copper cylinder. The average tissue thick- 
ness was determined by measuring the distance of the 
face of the applicator from the face of the cylinder. 
The thermal conductivities of all the tissues except 
epidermis were obtained by this procedure, since in 
view of the epidermal thinness the above method 
was not adaptable. 

The method of difference was used with epidermis. 
A section of well-shaved skin tissue consisting of 
dermis and epidermis was rigidly clamped to the 
copper cylinder, water at 55 C was poured over the 
skin, and the excess water was removed by blotting. 
The clamps prevented lateral contraction of the 
heated tissue and the hot water facilitated subse- 
quent removal of the epidermis. The conductivity 
determination was now made, the epidermis was then 
scraped off, and the determination repeated. As a 
further check, in certain experiments, a strip of in- 
tact epidermis was placed over the denuded dermis 
and the measurement repeated. The thickness of 
numerous pig epidermal strips was determined with 
a micrometer. The thickness was about 80 ± 10 /i- 

At least triplicate determinations were made on 
each of the four tissues of three different pigs (ap- 
proximately 10 kg). The average values of the thermal 
conductivities obtained on each of these tissues are 
given in Table 4. 


Table 4. In vitro thermal conductivities K of pig tissue, 
K given in (cal — cm)/(cm2 — min — degrees C) units. 



Epidermis 

Dermis 

Fat 

Muscle 

K 

0.036 

0.054 

0.021 

0.064 


0.023 

0.053 

0.024 

0.062 


0.032 

0.051 

0.023 

0.073 

K 

0.03 

0.053 

0.023 

0.066 


In view of the thinness and uncertainty in the 
thickness of the pig epidermis, the wide variation in 
the epidermal thermal conductivity was to be ex- 
pected. The data pertaining to the other tissues were 
considerably more reproducible. 

It is of interest to compare some of these data with 
those of Breuer,* who determined the respective 
thermal conductivities of both muscle and fat of cow, 
horse, pig, and dog. This investigator found that the 
conductivities of pig muscle and fat, expressed in the 
above units, were 0.060 and 0.021 respectively; fur- 
thermore essentially the same values were found for 


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STUDIES OF THERMAL INJURY 


CUTANEOUS AND SYSTEMIC 


the muscle and fat of the other three animals. In view 
of the excellent agreement between Brener’s value 
and the present one for pig muscle and fat, it is diffi- 
cult to understand the value, 0.03, that Hardy and 
Soderstrom report for both cow muscle and fat. 
Unfortunately no description of their experimental 
method was given. In order to investigate this dis- 
crepancy, the thermal conductivity of beef muscle 
was redetermined and an average value of 0.057, 
which checks Breuer, was obtained. 

In view of the numerous indeterminate factors 
(Section 17.3.1) which enter into the in vivo conduc- 
tion of heat through pig skin, the in vitro thermal 
conductivities of these four tissues are not of them- 
selves too useful. They do however serve as a base- 
line in the interpretation of certain experiments to be 
described. 

Observations {in vivo) of Caloric Uptake of Pig 
Skin and Rise in Temperature at Dermal-Fat 
Interface as a Function of Both Time and Skin 
Surface Temperature 

It was of interest to ascertain the caloric uptake of 
the skin when the epidermal surface was maintained 
at various temperature levels between 45 and 100 C. 
Numerous such experiments have been done and as 
was to be expected (see Section 17.3.1) the data were 
subject to wide variations and are extremely difficult 
to interpret in detail. Thus only a small fraction of 
these data will be reported and the variations to be 
expected will be indicated. During these experiments 
the temperature at the dermal-fat interface was also 
ascertained. 

A pig under Nembutal anesthesia was clipped and 
shaved. The hypodermic needle thermocouple was 
introduced laterally into the dermal-fat interface. 
The skin temperature at the chosen site was deter- 
mined and the automatic energy recording appli- 
cator wask applied. Thus a continuous record of the 
caloric up^ke of the skin at a predetermined epi- 
dermal surface temperature was obtained. The tem- 
perature at the dermal-fat interface was determined 
either intermittently with a Leeds & Northrup Type 
K2 potentiometer or continually with a General 
Electric photoelectric recording potentiometer. 

Caloric uptake rate of pig skin: Typical caloric up- 
take data as a function of time and epidermal surface 
temperature are presented in Table 5. 

The data given in Table 5 are a composite of at 
least three determinations on the lateral thoracic 
area of different pigs; five pigs in all were used. As 


Table 5. A guide ( +30 per cent) to the caloric uptake of 
the skin as a function of time and surface temperature as 
determined by the automatic energy recording applicator. 


Time inter- 
val in min 

45 C 

Skin surface temperature 

50 C 55 C 60 C 

65 C 

0-0.2 

Average caloric uptake rate 
6.0 9.5 12.0 

in cal/ min /cm^ 

15.0 17.0 

0.2-0.4 

2.2 

3.7 

4.9 

6.9 

8.4 

0.4-0.6 

1.8 

2.8 

3.8 

5.6 

6.7 

0.6-0.8 

1.7 

2.5 

3.1 

5.1 

5.9 

0.8-1 .0 

1.6 

2.3 

2.7 

4.7 

5.4 

1-1.5 

1.5 

2.0 

2.6 

4.3 

4.8 

1.5-2 

1.4 

1.8 

2.4 

4.1 

4.5 

2-3 

1.2 

1.6 

2.3 

3.7 

4.2 

3-5 

1.1 

1.5 

2.1 

3.2 

3.8 

5-7 

1.0 

1.4 

2.0 

2.8 

3.5 

7-10 

0.9 

1.3 

1.9 

2.5 

3.2 

0-1 

2.7 

Total caloric uptake in. cal/cni^ 
4.2 5.3 7.5 

8.7 

0-5 

7.5 

10.7 

14.3 

21.8 

25.2 

0-10 

12.2 

17.4 

24.0 

34.9 

42.7 


was expected, in view of the numerous factors (Sec- 
tion 17.3.1) that determine the caloric uptake in a 
living animal, the experimental variations inherent 
to similar exposures were considerable. Thus these 
data served only as a rough guide ( ± 30 per cent) to 
the caloric uptake rate of pig skin. 

It was noted that the average caloric uptake rate 
of pig skin during the first 0.2 minute was about six- 
fold greater than the average caloric uptake rate 
during the steady state period (7-10 minutes). This 
sixfold difference was due to the initial necessity of 
heat saturating the tissue and was primarily a heat 
capacity effect. After the first few minutes the skin 
tissue was essentially heat-saturated and the in vivo 
thermal conductivities of the various layers of pig 
skin primarily determined the caloric uptake rate. 
If the data given in Table 5 are plotted against time, 
the type of curve obtained will conform to that shown 
in Figure 2. A mathematical analysis of the general 
form of these curves based on equation (5) showed 
that during the first 2-3 minutes of the heat appli- 
cation. the skin can be considered as an infinite body 
with a ratio of thermal conductivity to heat capacity 
that is approximately the same as that computed 
from the in vitro determinations tabulated in Tables 4 
and 5. This agreement was probably due to the fact 
that the ratio of the thermal conductivity to heat 
capacity (equation 6) was not nearly so sensitive to 
the indeterminate in vivo factors considered in detail 
in Section 17.3.1 as the individual quantities them- 
selves. 


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BASIC CHARACTERISTICS OF HEAT AND HEAT TRANSFER 


317 


Table 6. The time dependence of the dermal-fat interface temperature ( ±20 per cent) during exposure of the surface of 
pig skin to predetermined temperatures. 


Time 


in 

min 

35.0 

45 

34.8 

50 

34.8 

55 

35.2 

60 

34.9 

65 

34.3 

70 

34.2 

80 

34.5 

90 





Dermal-fat interface temperature C 


0 

34.7 

34.5 

34.6 

35.0 

34.7 

34.2 

34.4 

34.8 

0.2 

36 

38 

39 

43 

46 

52 

53 

56 

0.5 

38 

43 

45 

46 

52 

62 

65 

66 

1.0 

39.5 

45 

47 

48 

53 

65.5 

71 

74 

1.5 

40 

47 

48 

47 

53 

66.5 

72 

77 

2.0 

40.5 

47 

49 

46 

54 

67 

74 

79 

3.0 

41 

47 

48.5 

45 

56 

67.5 

75 

79 

5.0 

42 

47 

47.5 

44.5 

58 

67.5 

77 


7.0 

42 

46.5 

47.5 

47 

58 




10.0 

42 

47 

48 

49 

59 








Average thickness of 

corium in mm 



2 

2 

2 

2 

2 

2 

2 

2 


2 

2.5 

3.2 

4.2 

3 

2.5 

2 

2 


0.06 

0.1 

0.09 

0.10 

0.16 





Surface temp C 
Initial 

During exposure 


Initial 

Termination of heat ex- 
posure 

In vitro thermal conduc- 
tivity of dermis at 
termination of expo- 
sure 


Interface Temperature at Junction of Dermis 
AND Fat 

The time dependence of the dermal-fat interface 
temperatures during the exposure of the skin surface 
to a predetermined temperature between 45 and 
90 C is given in Table 6. 

These values were a composite of at least two ex- 
perimental determinations on two different pigs 
(four determinations in all). As in the case of the 
caloric uptake measurements, the variations in dupli- 
cate experiments were considerable, and these data 
only serve as a rough ( + 20 per cent) guide to the 
time-temperature relationship at the dermal-fat 
interface. These data together with other experi- 
mental observations indicate the following. 

1. The junction of the fibrous dermis and the sub- 
dermal fat in lateral thoracic area of a lO-kg pig lies 
about 2 mm below the skin surface. Ten-minute ex- 
posures to surface temperatures of 50 to 70 C in- 
creased significantly the thickness of the dermis. This 
increase in thickness was due to the accumulation of 
edema fluid in the dermis and the effect was maximal 
when the skin surface was maintained at about 60 C. 
Skin surface temperatures of 45 C or below do not 
activate the mechanism which gave rise to edema. 
Skin surface temperatures equal to, or greater than, 
80 C denature the corium so rapidly that the mechan- 
ism by which edema fluid accumulated in the corium 
was destroyed. 

2. Although the continual caloric uptake by the 


skin tended to increase the dermal temperature, the 
appearance of relatively cool edema fluid tended to 
decrease it. At skin surface temperatures of 50 C and 
70 C, these two effects nearly counterbalanced each 
other, and after the first minute of heat exposure the 
dermal-fat interface temperature remained essen- 
tially constant. With skin surface temperatures be- 
tween 55 and 65 C the rapid appearance of a large 
amount of edema fluid more than compensated for 
caloric uptake, and the temperature at the interface 
between dermis and fat was temporarily lowered. 
This effect was maximal when the skin surface was 
maintained at about 60 C. 

3. When the skin surface temperature was main- 
tained at 45 C, and probably at all other tempera- 
tures that fail to cause edema, the dermis becomes 
“heat-saturated’’ after about 5 minutes of exposure. 
When edema fluid was produced, the time for dermal 
heat saturation was essentially indeterminate, but it 
apparently was greater than 10 minutes. *» 

4. Histological examinations showed that com- 
plete primary injury to the dermis was obtained in all 
experiments where the skin surface temperature was 
maintained at 65° or higher. These limited (5) 
time-temperature-injury data at the dermal-fat in- 
terface tended to indicate a quantitative relation- 
ship very similar to that found for epidermal injury 
(see Section 17.7). 

5. By making the reasonable assumption that the 
dermis is essentially “heat-saturated” at the end of a 


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318 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


10-minute heat exposure, the in vitro thermal con- 
ductivities of dermis can be computed by substitut- 
ing the approximate caloric uptake (Table 5), dermal- 
fat interface and skin surface temperatures, and the 
final dermal thickness into equation (3) (Section 
17.3.1); the neglect of the epidermal temperature 
drop introduced no appreciable error. Table 5 also 
shows the results of these calculations. 

A comparison of these values with the experi- 
mentally determined in vitro values (Table 4) for pig 
dermis indicated that the presence of edema fluid 
increased the thermal conductivity of dermis two- 
to threefold. This increase in conductivity, however, 
was slightly more than compensated by the swelling 
of the dermis; an edematous dermis is thus a some- 
what better heat barrier to the underlying tissues 
than normal dermis. A comparison of the in vivo 
thermal conductivity obtained at 45 C with the 
in vitro value of 0.053 (see Table 4) tends to indicate 
that intact circulation probably increased the effec- 
tive thermal conductivity of dermis by about 15 per 
cent. 

Estimation of Temperature Changes at 
Epidermal-Dermal Interface during Exposure 
OF THE Skin Surface to Heat 

In view of the thinness (^^80 ju) of the pig’s epi- 
dermis, the experimental measurement of the time- 
temperature relationships at the epidermal-corium 
junction was not feasible. 

There are certain facts, however, that allowed the 
estimation of this time-temperature relationship with 
a considerable degree of certainty. In view of the ex- 
treme thinness of epidermis, the temperature of the 
basal layer was largely determined by skin surface 
temperature, which was an accurately known quan- 
tity. This is most readily seen by solving heat con- 
duction equation (3) for steady-state temperature of 
the basal epidermal layer. Of the four necessary ex- 
perimental quantities, namely, skin surface tempera- 
ture, epidermal thickness (about 80 m), epidermal 
thermal conductivity (Table 4), and caloric uptake 
of the skin at the requisite skin surface temperature 
(Table 5), only the last two were subject to a con- 
siderable variation ( ±30 per cent). Fortunately, even 
variations of this magnitude resulted in uncertain- 
ties of less than 0.2 C in the steady-state tempera- 
ture of the basal epidermal layer. 

Basal Epidermal Temperatures When the Skin Sur- 
face is Immediately Brought to and Maintained at a 
Temperature between 45 C and 100 C. Before the 


steady-state temperature is attained, the time-tem- 
perature relationship at this epidermal-dermal junc- 
tion is given under these conditions to a good approx- 
imation by equation (6c) of Section 17.3.1, where y 
has the following numerical value: 

y = 0.15 

if the time t is expressed in seconds. 

The numerical constant, 0.15, is not subject to the 
experimental uncertainties of the quantities requisite 
to computation by equation (6a), since it can be 
quite accurately determined empirically from the 
temperature-time-epidermal injury data (see Sec- 
tion 17.6.5 for details). An identical value for y can 
also be directly computed by substituting into equa- 
tion (6c) the experimentally determined values for 
heat capacity, thermal conductivity, and thickness 
of epidermis, and by assuming an epidermal density 
of 0.8 g/cc (a most reasonable value). In view of the 
two completely independent methods, one of which 
was in vivo and the other in vitro, considerable confi- 
dence could be placed in the adaptation of the in- 
finite body picture (see Section 17.3.1) to the solution 
of the time- temperature relationship at the epi- 
dermal-dermal junction during the unsteady state 
period of heat flow. 

The computation of the temperature of the basal 
cell layer of the epidermis as a function of both time 
and skin surface temperature is given in Table 7 A. 

Table 7A. The computed time-temperature relation- 
ships for the epidermal-dermal interface when the skin 
surface is immediately brought to and maintained at a 
specific temperature. 


Time Surface temperature, C 

in 45 55 65 80 100 

seconds Temperature at basal epidermal layer* C 


0 

35.0 

35.0 

35.0 

35.0 

35.0 

0.01 




36.3 

37.0 

0.02 



38.9 

40.9 

43.4 

0.05 


41.8 

45.2 

50.3 

57.1 

0.1 

40.1 

45.2 

50.3 

57.9 

68.2 

0.2 

41.3 

47.6 

53.9 

63.3 

75.9 

0.5 

42.7 

50.4 

58.1 

69.6 

85.1 

1.0 

43.3 

51.6 

60.0 

72.4 

89.1 

2.0 

43.8 

52.6 

61.4 

74.6 

92.3 

5 

44.2 

53.5 

62.7 

76.6 

95.1 

10 

44.5 

53.9 

63.4 

77.6 

96.6 

30 

44.7 

54.4 

64.1 

78.6 

98.0 

60 (1 min) 

44.8 

54.6 

64.4 

79.0 

98.6 

120 (2 min) 

44.9 

54.9 

64.5 

79.4 

99.2 

300 (5 min) 

44.9 

54.9 

64.7 

79.5 

99.3 

600(10 min) 

44.9 

54.9 

64.8 

79.7 

99.6 

Steady 

44.8 

.54.5 

64.2 




state] 


* Computed by equation (6c) and experimental data of Section 3.2. 
t Computed by equation (3) and experimental data of Section 3.2. 


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BASIC CHARACTERISTICS OF HEAT AND HEAT TRANSFER 


319 


Table 7B. The computed time-temperature relation- 
ships for the epidermal-dermal interface when an entire 
animal (~30 cm in diameter) is surrounded by an en- 
velope of ambient and radiant heat that results from a 
constant temperature source. 


Time 

in 

seconds 

Circumambient temperature, C 

80 100 125 150 175 

Heat transfer coefficient H* in 
cal/cm^/min per C 

0.015 0.019 0.021 0.024 0.026 

Temperature at basal epidermal layer, Ct,f 

0 

35 

35 

35 

35 

35 

10 

37 

39 

40.5 

44 

46 

20 




46.5 

49 

30 

38.5 

41.5 

44 

49 

52 

40 




51 

54.5 

50 

39.5 

43.5 

46.5 

53 

57 

70 

40 

44 

48 

56 

60 

100 

41 

45.5 

50 

59 

64 

130 

42 

47 

52 

61 


160 

42.5 

48.5 

54.5 

63 


200 

43 

50 

56 

65 


300 

45 

52.5 

59 



400 

46 

55 

63 



500 

47 





600 

48 





800 

50 





1,000 

50.5 





1,200 

51 






* In order to make these data directlj" comparable to the experimental 
investigations of Section 17.9, the radiant contribution to H was computed 
by using a source temperature 20 per cent in excess of the air temperature. 

t Computed by means of equations (5), (6), (6a), and (6b) and experi- 
mental data of Section 17.3.2. 

t Because of both the thinness of the epidermis and the slow rate of heat 
transport to the skin, there is no appreciable difference between these 
temperatures and those of the skin surface after the first 20 seconds of heat 
exposure. 

The data given in Table 7 A show that there was a 
rapid rise in the temperature of the basal epidermal 
layer when the skin surface was immediately brought 
to and maintained at a specified constant tempera- 
ture. A comparison of the unsteady-state data com- 
puted from equation (6c) with the steady-state data 
obtained by means of equation (3) showed that the 
epidermis under the above conditions became essen- 
tially “heat-saturated’’ after a heat exposure of 
0.5- to 1.0-minute duration. 

Actually, only the unsteady-state time-tempera- 
ture relationship as given by equation (6c) need be 
considered to elucidate the irreversible epidermal in- 
jury threshold data of Section 17.6.5; since these ex- 
perimental time-temperature-epidermal injury rela- 
tionships were such that for all skin surface tempera- 
tures above 50 C the epidermis never reached heat 
saturation, and for all temperatures below 50 C the 
difference between the steady-state basal epidermal 


temperature and the skin surface temperature was 
trivial. 

It must be re-emphasized that these data apply 
only to situations in which the heat transfer coeffi- 
cient H from the temperature source to the skin sur- 
face is infinite.® In all cases where H is finite an analy- 
sis similar to that given below is required. 

Basal Epiderynal Temperatures When the Entire 
Animal Is Surrounded hy an Envelope of Ambient and 
Radiant Heat between 80 and 175 C. In the previous 
section, the time-temperature relationships at the 
epidermal-dermal junction depended only upon the 
rate of heat transfer through the skin and the con- 
stant temperature of the heat source. To this must 
now be added the slow rate at which heat is trans- 
ported from the heat source to the skin surface via 
air conduction, air convection, and infrared radi- 
ation. The mathematical solution of this problem is 
given by equation (6), where the only quantity that 
requires further consideration is H, the heat transfer 
coefficient from the heat source to the skin surface. 
This quantity is readily computed through the sub- 
stitution of equation (1), heat transfer by convection, 
and equation (2), heat transfer by radiation, into 
equation (5) . The numerical values of the heat trans- 
fer coefficient which were obtained at certain source 
or air temperatures are shown in Table 7B. A com- 
parison of the numerical values of H, 0.015 to 0.026 
calorie per square centimeter per minute per C, with 
epidermal thermal conductance K/L (Table 4) nu- 
merically equal to 4 in the same units, indicates the 
slow rate at which ambient and radiant heat is trans- 
ferred to the skin surface as compared with the rate 
this heat flows through the epidermis. 

Table 7B also gives the estimated temperature of 
the basal epidermal cell layer as function of source or 
air temperature as calculated by means of equation 
(6). These data show the extreme slowness of tem- 
perature rise at this epidermal-dermal junction. In 
fact, under these conditions, the epidermal tempera- 
ture even after a heat exposure of 15 minutes is far 
lower than the temperature of the heat source, and 
one would expect an animal to succumb to hyper- 
thermia long before the temperature of the skin 
approached that of the air. 

Although the data for the time-temperature rela- 
tionship at the skin surface are not given, they can be 

® Under the experimental conditions to be described in 
Section 17.6 (hot water experiments), H is not infinite but 
rather about 10^ cal/cm^/min per C. In these computations 
the substitution of oo for 10^ is of no significance. 


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320 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


readily computed by putting L (the thickness of the 
epidermis) equal to zero in equation (6). If this be 
done, it will be found that, except for the first 20 
seconds of heat exposure, the skin surface tempera- 
ture is not significantly different from the values re- 
corded in Table 7B for the basal epidermal tempera- 
ture. This is due to the fact that heat transfer to the 
skin is the controlling factor. Thus, these data can 
also be taken as the temperature of the skin surface 
as a function of time. 

A comparison of Tables 7 A and 7B indicates the 
importance to the epidermal time-temperature rela- 
tionships of the mode of imparting heat to skin sur- 
face. Thus, for a given source temperature, a mecha- 
nism that enables the surface temperature to be im- 
mediately brought to and maintained at the source 
temperature has, on a time basis, at least a thousand 
times greater injury propensity to epidermis than a 
heat source which raises the skin temperature by 
means of radiation, conduction, and convection of 
relatively immobile air. (See Section 17.9.2 under 
“Measurement of Heat Transfer.’’) 

17.3.3 Summary 

The various physical factors which determine the 
transfer of heat energy to and through the skin and 
the temperatures attained thereby have been de- 
fined and discussed. 

A general theory of heat flow through the epi- 
dermis is developed. 

Experimental observations pertaining to the rate 
at which heat energy is taken up by the skin during 
surface exposures of varying intensity and the sub- 
surface thermal gradients established therein have 
been presented. 

The time-temperature relationship at the dermal- 
epidermal junction is computed under two greatly 
different experimental conditions: (1) when the skin 
surface temperature is immediately brought to and 
maintained at the temperature of the heat source, 
and (2) when the entire skin surface is exposed to a 
specified circumambient and circumradiant temper- 
ature. These data indicate the extreme importance of 
the mode of applying heat to the skin surface to the 
time-temperature relationships within the epidermis. 

17.4 EFFECTS OF INHALED HEAT 

It was inferred from the results of the pilot experi- 
ments (Section 17.2.5) that, so far as rapid neutral- 
ization of enemy personnel by flame thrower attack 


is concerned, the effects of heat on the surface of the 
body are probably of greater importance than are its 
effects on the air passages and lungs. The implication 
of this assumption is too great to accept at face value 
the small amount of evidence provided by the pilot 
experiments. 

A search of the literature failed to disclose any re- 
liable information concerning the effects on the lungs 
and air passages of inhaled heat or the circumstances 
in which thermal injuries of the respiratory tract 
may be sustained. The following investigation was 
accordingly undertaken.^’ 

17.4.1 Experimental Procedure 

In order to study the effects of heat on the respira- 
tory tract independently of the secondary changes 
that might result from concomitant burning of the 
skin, dogs were caused to breath hot air which was 
conducted directly to the trachea through an in- 
sulated transoral cannula. 

In some experiments heated air was pumped di- 
rectly into the air passages and in others it was in- 
haled by the respiratory efforts of the animal. The 
inner end of the cannula extended below the vocal 
folds of the larynx. Three types of inhalation experi- 
ments were performed. In the first the animals 
breathed room atmosphere heated to temperatures 
as high as 500 C in an oven. In the second, flame 
from a blast burner at temperatures estimated to be 
in the vicinity of 1000 C was directed into the ex- 
ternal end of the cannula. In the third, a mixture of 
live steam and air was breathed from a generator 
(see Figure 5) . All experiments were conducted un- 
der anesthesia induced by the intravenous or intra- 
peritoneal injection of sodium pentobarbital. 

The external temperature of the air available for 
respiration in each type of experiment was measured 
either by a thermometer or a platinum-rhodium 
thermocouple. Thermocouples (40 gauge copper- 
constantan) were installed in the airway, one at the 
laryngeal end of the transoral cannula and the other 
at or near the bifurcation of the trachea, to measure 
the rate at which the inhaled air was cooled. Leads 
from these thermocouples were connected with a 
Mohl galvanometer having a period of 0.2 second. 
The excursions of the galvanometer were observed 
directly and recorded manually. 

17.4.2 Rate of Cooling of Inhaled Air 

When the superheated air was inhaled, the tem- 
perature recorded by both the laryngeal and the 


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EFFECTS OF INHALED HEAT 


321 



Figure 5. Experimental procedure used to investigate effects of inhaled heat on air passages and lungs. In all instances, 
insulated cannula conveyed hot air, flame, or steam from outside to animal’s larynx. Position of intra-laryngeal and 
deep tracheal thermocouples is shown. Top left view: Animal breathed room temperature heated in oven to 350 C. Top 
right view: Room temperature was pumped into animal’s lungs from combustion oven which was heated to 500 C. 
Bottom left view: Flame and combustion products of blast burner were projected into cannula during each inspiration. 
Bottom right view: A 400 ml blast of mixture of live steam and air was released into transoral cannula at the beginning 
of each inspiratory effort. Results of these experiments are shown in Table 8. 


Table 8. Results of experiments in breathing of hot air. 


Max 

Original pre- temperature 

inspiratory recorded (C) Site and severity of injury 


Kind of 
atmosphere 
breathed 

No. 

Animal 

No. 

temp of air 
(C) 

(approximate) 

No. of 
breaths 

Laryn- 

geal 

cannula 

Lower 

trachea 

Recovery 

period 

(hours) 

Upper 

trachea 

Lower 

trachea 

Lungs 

Air from dry- 

1 

423 

350 

46 

182 


19 

Mild 

None 

None 

ing oven. 

2 

420 

350 

52 

180 

• • • 

19 

Mild 

None 

None 

See Fig. 5 A 

3 

391 

350 

103 

159 

• • • 

30 

Mild 

None 

None 

4 

390 

350 

106 

175 


Not 

killed 

(Complete clinical recovery — 
no autopsy) 

Air from com- 

5 

392 

500 

60 

267 

• • • 

4 

Mild 

None 

None 

bustion oven. 

6 

432 

500 

44 

327 

50 

7 

Moderate 

None 

None 

See Fig. 5B 

7 

426 

500 

22 

291 

• • • 

24 

Mild 

None 

None 

8 

431 


17 

• • • 

135 

7 

Moderate 

Mild 

None 

Flame from 

9 

433 


10 

327 

51 

8 

Severe 

Moderate 

Mild 

blast burner. 

10 

454 


16 

540 

100 

11 

Severe 

Mild 

None 

See Fig. 5C 

11 

455 


24 

550 

65 

24 

Moderate 

Mild 

None 

12 

405 


14 

510 

64 

Not 

killed 

(Complete clinical recover}'’ — 
no autopsy) 

Steam from 

13 

456 

Over 100 

27 

106 

59 

6 

Moderate 

Mild 

None 

generator. 

14 

519 

Over 100 

18 

98 

79 

7 

Severe 

Moderate 

None 

^e Fig. 5D 

15 

481 

Over 100 

20 

94 

53 

10 

Severe 

Severe 

Severe 

16 

475 

Over 100 

16 

99 

94 

10 

Severe 

Severe 

Severe 


17 

524 

Over 100 

10 

• • • 

90 

24 

Severe 

Severe 

Moderate 


18 

522 

Over 100 

12 


75 

48 

Severe 

Severe 

Mild 


tracheal thermocouples rose throughout inspiration 
and fell during expiration. In each situation the high- 
est point in the temperature curve was reached at or 
near the end of inspiration. The inhaled gas lost most 
of its heat before reaching the lungs. When the in- 
haled gases were relatively dry, the intratracheal 
temperature rose to a sharp peak and fell away 


rapidly during expiration. When steam was inhaled, 
the curve described a plateau rather than a peak, 
probably because of the condensation of hot water on 
the thermocouple. The results of these experiments 
are shown in Table 8. 

When air heated to between 350 and 500 C was in- 
haled, the temperature fell to about half of its ex- 


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322 


STUDIES OF THERMAL INJURY — CUTANEOUS AND SYSTEMIC 



Figure 6. Thermal laryngitis and tracheitis without 
pulmonary injury. Photograph of respiratory tract of 
dog 24 hours after inhalation of flame. Sufficient heat 
had been conducted through wall of cannula to cause 
mild degree of laryngeal edema which may be recog- 
nized by bilateral olive-shaped mucosal protrusions 
from ventricular recesses. There was extensive destruc- 
tion of mucosa of upper trachea, diminishing rapidly to 
mild catarrhal inflammation in lower third. No abnor- 
mality of bronchi or lungs of this animal was recog- 
nized. 

ternal level by the time it reached the larynx, despite 
the fact that it was conducted through the mouth by 
means of an insulated cannula. By the time it had 
reached the bifurcation of the trachea, the tempera- 
ture had dropped to approximately 50 C. Flame and 
combustion products of a blast burner directed into 
the external end of the transoral cannula were de- 
livered to the larynx at temperatures between 300 
and 550 C. The highest recording at the bifurcation 



Figure 7. Thermal tracheitis and pneumonitis. 
Photograph of respiratory tract of dog 10 hours after 
inhalation of steam, showing severe tracheobronchitis 
with dilatation of bronchi. There is central hemorrha- 
gic pneumonitis with generalized pulmonary edema and 
hyperemia. 


of the trachea in such experiments was 135 C. When 
a mixture of live steam and air was inhaled, the in- 
spiratory peaks recorded at the laryngeal opening of 
the cannula ranged between 94 and 106 C and those 
by the deep tracheal thermocouple, between 53 and 
94 C. 

17.4.3 Effects on Animals 

The mildest thermal exposure used in the inhala- 
tion experiments was more than sufficient to cause 
severe injury to the skin. Every animal included in 
Table 8 would have sustained severe cutaneous in- 
jury if the skin had been exposed for more than a few 


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EFFECTS OF INHALED HEAT 


323 


seconds to such temperatures. Circumambient air 
temperatures as low as 300 C produce severe injury 
of unprotected skin within a few seconds. Mixtures 
of steam and air at 100 C destroy epidermis even 
more quickly. 

Early in the investigation it was found that if ani- 
mals were to survive the inhalation experiments long 
enough to develop reactive changes in the lower air 
passages it was necessary to protect the larynx. 
Otherwise they died prematurely of asphyxia due to 
laryngeal edema. For this reason the transoral can- 
nula was inserted well below the glottic folds. 

Primary thermal injury of the lungs occurred in 
none of the 7 animals that breathed hot air, in only 1 
of the 5 animals that inhaled flame from a blast 
burner, and in 4 of the 6 animals that inhaled live 
steam. In the remaining animals thermal injury to 
the respiratory tract was conflned to the upper air 
passages. In no instance did an animal die as a result 
of thermal injury of the lungs within the first 24 
hours. All animals that sustained thermal injuries of 
the respiratory tract would, under nonexperimental 
conditions, have received severe cutaneous burns. 

Mucosal necrosis with desquamation of surface 
epithelium occurred in all instances where the blast of 
hot atmosphere first struck the lower portion of the 
larynx and the upper portion of the trachea. In the 
case of hot air the injury was usually localized and 
represented by shallow ulceration associated with 
catarrhal inflammation of the upper third of the 
trachea (Figure 6). Inhalation of flame or steam led 
to extensive destruction of the trachea with edema 
of the peritracheal areolar tissue of the neck and 
mediastinum and detachment of large casts of ne- 
crotic mucous membrane, which were either expelled 
by coughing or subsequently inhaled into the lower 
portions of the respiratory tract (Figure 7). 

The portions of the lungs most vulnerable to in- 
jury were the centrally located alveolar ducts and 
their communicating alveoli (Figure 8). Atmosphere 
not hot enough to damage the mucosa of the large 
bronchi or the alveoli of the more peripheral portions 
of the lungs was in some instances capable of causing 
central pulmonary edema and both intra-alveolar 
and interstitial hemorrhage. After more severe ex- 
posures the lungs became diffusely edematous and 
hemorrhagic. Focal patches of atelectasis and em- 
physema were observed and in some instances were 
obviously due to aspiration of mucus or mucosal 
debris. Bronchopneumonia was commonly observed 
in animals that had received tracheal burns. It ap- 


peared that, regardless of the mildness of the pri- 
mary thermal injury of the lungs, if the inhaled air 
was hot enough to damage the trachea it usually 
predisposed the animal to pneumonia. 

17.4.4 Discussion 

It was apparent from the foregoing observations 
that air hot enough to burn the skin can be inhaled 
without causing damage to the trachea or lungs and 
that if the temperature of the air is high enough to 
damage the respiratory passages it will inevitably 
have caused burning of the surface of the body. 

This observation seemed paradoxical in view of the 
fact that the mucosa of the air passages is much 
thinner than the skin and should therefore be more 
vulnerable to thermal injury. The explanation of the 
experimental findings lies in the fact that the quan- 
tity of heat that can be stored in the volume of gas 
that constitutes a breath is remarkably small. At any 
given air temperature the number of calories that can 
be transferred to the respiratory tract incident to the 
inhalation of a breath of hot air is limited by the vol- 
ume of that breath, whereas convection currents are 
capable of bringing a practically unlimited volume of 
hot air in contact with the skin. An infinitely greater 
caloric transfer can occur for each unit of surface 
exposed. 

Not only is the amount of heat energy available 
for transfer to the skin greater than that which is 
available for transfer to the respiratory membranes 
but also there are important time differences be- 
tween cutaneous and respiratory exposures. In the 
case of the skin the exposure is virtually continuous, 
whereas the lining of the air passages is exposed in- 
termittently as each new breath is inhaled. 

An instructive illustration is provided by calcu- 
lating the potential heat transfer to the respiratory 
•tract that might occur if air were inhaled at 142 C. 
Let it be assumed that the amount inhaled with each 
breath would be sufficient to increase the pulmonary 
volume by 500 ml, that the air was dry when inhaled 
and saturated with moisture when exhaled, and that 
it was cooled to body temperature by the time it left 
the body. Approximately 13 cal of heat energy 
could be released within the body by cooling of one 
such breath from 142 to 38 C. Theoretically this 
amount of heat would be sufficient to raise the tem- 
perature of 1 g of tissue by approximately 13 degrees, 
providing none of it was carried away by the blood 
circulating in the subsurface capillaries. Actually no 
change in the net temperature of the respiratory 


SECRET 


324 


STUDIES OF THERMAL INJURY — CUTANEOUS AND SYSTEMIC 



Figure 8. Primary thermal pneumonitis. Photomicrograph of lower lobe of dog’s lung 24 hours after inhalation of 
steam. Although there was severe tracheitis, primary and secondary bronchi showed remarkably little change. Evidence 
of pulmonary injury was confined largely to the central portions of lobes and consisted of hyperemia, edema, and partial 
atelectasis. 


tract would occur in such circumstances because the 
gain of 13 cal would be offset by a loss of 13 cal inci- 
dent to the evaporation of the 23 mg of water that 
would be required to saturate that amount of dry air. 

This is not to imply that the inhalation of air 
heated to 142 C would be necessarily harmless. Desic- 
cation would probably occur near the portal of entry 
even though there were no net change in the temper- 
ature of the respiratory tract as a whole. The calcu- 
lation serves to emphasize how important the heat 
capacity of the inhaled gas is in relation to the prob- 
lem of thermal injury of the lungs. A rise in tissue 
temperature is prerequisite to the occurrence of 
thermal injury and the amount that the tissue tem- 


perature is raised incident to any given exposure will 
depend in part on the magnitude of temperature dif- 
ferential and in part on the amount of heat energy 
that the inhaled gas is capable of storing. 

A more important attribute of an inhaled hot gas 
than its temperature in relation to its capacity to 
cause thermal injury is its water content. When 
steam or a mixture of steam and air comes in contact 
with a cool surface such as the skin or the lining of 
the respiratory tract, water is condensed on the sur- 
face with liberation of a relatively large amount of 
heat. 

Thus the cooling of a 500-ml mixture of equal 
parts of steam and air from 125 to 38 C would lead 


SECRET 


COMPARISON OF PORCINE AND HUMAN SKIN 


325 


to the condensation of about 300 mg of water. The 
heat energy liberated by this amount would be in the 
neighborhood of 175 cal. There is little doubt but 
that the sudden liberation of 175 cal to the lining of 
the air passages or on the surface of the skin would 
be capable of causing some injury. 

17.4.5 Summary 

It was apparent from these experiments that ther- 
mal injury of the lungs is probably a negligible factor 
in the causation of disability or death incident to 
exposure to conflagrations such as might result from 
flame thrower action. A thermal exposure of suffi- 
cient intensity to cause direct injury of the lungs was 
more than sufficient not only to cause extensive burn- 
ing of unprotected skin but also to result in rapidly 
fatal obstructive edema of the glottis. In the case of 
externally unburned or mildly burned casualties of a 
flame attack it can be assumed that no significant 
thermal injuries of the respiratory tract have been 
sustained. 

17.5 COMPARISON OF PORCINE AND 

HUMAN SKIN 

The original choice of the pig as a suitable subject 
for this investigation was based on the fact that no 
other readily available animal has skin that bears so 
close an anatomical resemblance to that of man. 

A comparison of the structural characteristics of 
porcine and human skin at this point seems desirable 
in view of the extent to which the pig was used in ex- 
periments designed to provide information regarding 

(1) the reciprocal relationship of time to temperature 
in the production of cutaneous injuries in man, and 

(2) the local and systemic disturbances in man which 
cutaneous hyperthermia may be capable of causing. 

Like that of man the surface of the pig’s body is 
covered by three layers of tissue. Progressing from 
outside in, these are the epidermis comprising strati- 
fied epithelial cells, the dermis comprising fibrous 
connective tissue, the hypodermis comprising fibrous 
connective tissue, and the hypodermis comprising 
fibroadipose tissue (see Figures 9 and 10). 

17.5.1 Epidermis 

The epidermis of the pig varies in thickness, the 
average over the lateral body surface of immature 
animals (8-12 kg) being approximately 0.1 mm, 
which is slightly less than that from corresponding 
areas of adult human subjects. As with man there 
are irregularities in contour of both the upper and 


lower surfaces of the epidermis, those on the upper 
surface being due to an intricate system of intercom- 
municating linear depressions and those on the lower 
surface corresponding to the dermal papillae over 
which it is moulded. The hairs penetrating the epi- 
dermis of the pig are thicker and more numerous 
than those of man. 

Microscopic appearance of epidermis : Like that of 
man the outermost zone of epidermis or stratum 
corneum of the pig consists of several loosely con- 
nected layers of the desiccated and intensely baso- 
philic remains of keratinized epithelial cells. 

The second or granular layer is thin and consists of 
several layers of dead or dying squamous cells, the 
acidophilic cytoplasm of which contains many fine, 
deeply basophilic kerato-hyaline granules. Many of 
these cells have lost their nucleuses. Others contain 
shrunken hyperchromatic nucleuses or Feulgen nega- 
tive nuclear ghosts. 

The third zone is comprised of several layers of 
aging squamous cells which no longer have any direct 
cytoplasmic attachment to the dermis. The cyto- 
plasm is dense, deeply acidophilic, and appears des- 
iccated. The cells are so closely packed that neither 
intercellular bridges nor spaces can be recognized. 
Many of the nuclei are relatively small and more 
densely packed with chromatin granules than those 
of the deeper cells. 

The fourth zone consists of cells in transition be- 
tween the squamous and the basal cell layer. The 
transitional cells are large and polyhedral and many 
of them still have an attenuated footlike cytoplasmic 
attachment to the dermis. It is in this zone that in- 
tercellular bridges of tonofibrils are most readily 
visualized. The cytoplasm is moderately basophilic. 
The cell outlines are distinct and the intercellular 
spaces are clearly defined. The nuclei are larger and 
rounder than those of the more superficial cells and 
contain several coarse and many fine granules of 
chromatin. 

The fifth zone is comprised of the basal cells, 
which, except for their cuboidal or columnar shape 
and their palisadelike arrangement on the dermis, 
are essentially similar to the overlying transitional 
cells. Projecting from the inferior surface of the basal 
epidermal cells of the pig are many robust tono- 
fibrils which appear to be embedded in the dense felt 
work of fine collagen fibrils that comprise the super- 
ficial zone of dermis. No such fibrillar anchorage of 
epidermis to dermis can be seen in human skin (see 
Figures 19 and 20). 


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326 


STUDIES OF THERMAL INJURY — CUTANEOUS AND SYSTEMIC 




Figure 9 Figure 10 

Appearance of porcine (Figure 9) and human (Figure 10) skin under low magnification, stained with phloxine-methylene 
blue. Sections are representative of lateral thoracic region of pig and lateral abdominal region of man. Epidermis is 
slightly thicker in man, and dermal papillae are broader in pig. Collagenous bundles in dermis of pig are heavier than 
those in man. Glands shown in hypodermis of pig do not secrete sweat. 


The microscopic appearance of the epidermis of 
both man and pig suggests that there is a progressive 
loss of intracellular water as the epithelial cells grow 
older and move away from the dermis. The nearer 
the surface is approached, the more desiccated the 
cells appear. The entire stratum corneum and most 
of the cells of the granular layer appear to be dead 
and incapable of vital reaction (see Figures 17 
and 18). 

17.5.2 Dermis 

The dermis covering the lateral body surface of 
immature pigs measures between 1.0 and 2.0 mm in 


thickness and is generally more compact than that 
of man. In both pig and man the superficial portion 
of the dermis comprising the papillary layer or 
corium is characteristically a soft, thin, loosely ar- 
ranged felt work of delicate collagen fibrils in which 
there appears to be an abundant amount of inter- 
stitial fluid. In man it is readily distinguishable from 
the thick underlying reticular layer, which is com- 
prised of robust and closely interwoven bundles of 
collagen fibrils. Elastic fibrils are more numerous in 
human than they are in porcine skin. On the lateral 
body surface of the pig the corium tends to be thinner 
and less well defined than it is in man and in places is 


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COMPARISON OF PORCINE AND HUMAN SKIN 


327 



Figure 11. Series of composite photomicrographs showing vascularization of block of hyperemic porcine skin which 
measured 2x2x2 mm. Series of thick (50 ju) benzidine-treated horizontal and vertical sections were mounted in such a 
way as to show distribution of veins, arteries, and capillaries at various levels beneath surface. No. 1 shows capillary 
plexus lying in most superficial (50 m) portion of dermis. No. 6 shows vessels in most superficial layer of adipose tissue of 
hypodermis. 


only slightly less compact than the reticular zone. 
The deeper portion of the reticular connective tissue 
sends trabecular extensions into the underlying adi- 
pose hypodermis. 

Blood Vessels of Porcine Skin 

It was observed in ordinary histological prepara- 
tions that the appearance of the capillaries in the 
dermal papillae of the body skin of the pig is similar 
to that in corresponding regions of man. In recog- 
nition of the fact that it is difficult or impossible to 
get an accurate impression of so complicated a 
structure as a capillary network by two-dimensional 
visualization, a modification of the Pickworth tech- 
nique was employed in order that the dermal blood 
vessels could be studied in three dimensions. 

Maximum cutaneous hyperemia was induced be- 
neath a circumscribed area of the lateral body sur- 
face of the pig by exposure to water at 50 C for 
20 minutes. After such an exposure the erythrocytes 


were so densely packed in the distended capillaries 
that there was practically no loss of blood from them 
when the skin was excised. Skin and subcutaneous 
tissue treated in this way was excised to a depth of 
8 mm, fixed in 10 per cent formalin, cut in thick 
sections, and treated with benzidine. 

The benzidine combined with the hemoglobin to 
impart a dark blue color to the contents of the en- 
gorged vessels. After skin treated in this manner was 
cleared, a three-dimensional study of its blood vessels 
could be made by use of a binocular microscope. 

The appearance of the dermal vessels of porcine 
skin at various levels below the surface is shown in 
Figure 11. To prepare this illustration a block of 
benzidine-treated skin was cut serially and parallel 
to the surface in sections measuring 50 n in thick- 
ness. Another block of the same skin was cut serially 
and at right angles to the surface. Photographs were 
made of both series and the prints were mounted in 
such a manner as to orient the horizontal sections in 


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328 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


relation to the depth below the surface that each 
represented. 

The epidermis was removed from the surface of the 
block of skin shown in Figure 11. The excised skin 
was not clamped prior to fixation and postexcisional 
contraction resulted in an accentuation both in the 
height of the dermal papillae and also in the thick- 
ness of the dermis. It may be seen that the fibrous 
dermis including the papillae measures approxi- 
mately 2 mm in thickness and that broad septa of 
fibrous connective tissue extend down from the der- 
mis at more or less regular intervals into the under- 
lying fat. 

In approaching the surface the blood vessels to the 
skin followed an oblique course through the hypo- 
dermis and after reaching the lower layer of the 
fibrous dermis branched horizontally with multiple 
intervenal and interarterial anastomoses. From these 
first approximately horizontal plexuses originated a 
series of broad vascular loops that penetrated to the 
mid-portion of the dermis. Interarterial and inter- 
venal anastomoses between these loops served to 
establish a mid-dermal plexus. From this mid-dermal 
plexus originated numerous hairpin-shaped capillary 
loops which extended upward into the dermal papil- 
lae. These capillary loops anastomosed freely with 
one another and constituted the most superficial or 
papillary plexus. It was apparent that capillary com- 
munications between the arterioles and venules oc- 
curred at different levels. Some followed a course 
that brought them to within a few microns of the 
basal epithelial cells over the tips of the papillae. 
Still others followed an almost horizontal course to 
establish communications between the arterioles and 


venules of the intermediate plexus. At all levels 
through the dermis there were numerous vascular 
communications with the mantlelike meshwork of 
capillaries that surrounded the hair follicles and 
dermal glands. 

As may be seen in Figure 11 the number, size, dis- 
tribution, and communications of the dermal blood 
vessels of the pig are remarkably similar to those de- 
scribed by both Lewis and Spalteholz in human 
skin. The similarity of blood vessels in human and 
porcine skin was found to be so great that it was with 
difficulty that one could be distinguished from the 
other in Pickworth preparations. 

It is not intended to imply that the anatomical re- 
semblance between the vessels of human and porcine 
skin implies an equal degree of functional similarity. 
Certainly the vascularization of both indicates that 
ample and similar mechanical facilities exist either 
for the transfer of body heat to the surface to facili- 
tate its dissipation, or for the conduct of surface heat 
to the interior to raise the internal temperature of 
the body. 

Sweat Glands and Sweating 

Several types of glands are encountered in the 
dermis and hypodermis of the pig and, although one 
of them bears some resemblance to the sudoriferous 
glands of human skin, it does not secrete a significant 
amount of sweat. 

The fact that the pig does not sweat was verified 
by a series of experiments in which the water loss 
from the skin of living pigs was measured at various 
environmental temperatures, with and without the 
administration of pilocarpine (see Table 9). 


Table 9. Rate of water loss from surface of human and porcine skin. Amount of water loss determined by accretion in 
weight of Mg ( 0104)2 contained in base of weighing bottle during the time that the neck of the bottle was held in contact with 
the skin. 


Water uptake (mg/cm-/min) during a period of 10 minutes 
Temp 21 c — Humidity 30-40% Temp 36 C — Humidity 30-40% 

No. of No. of 

tests Min Max Mean tests Min Max Mean 


Dead pig (lateral thoracic region) 
Live pig (lateral thoracic region) 

4 

0.016 

0.026 

0.019 

4 

0.023 

0.031 

0.027 

Without pilocarpine 

Live pig (lateral thigh) 

5 

0.016 

0.020 

0.021 

6 

0.020 

0.032 

0.028 

Without pilocarpine 

. 

.... 



4 

0.018 

0.028 

0.024 

With pilocarpine* 

(1 mg/kg bwt) 

Live man (forearm) 

• 




4 

0.021 

0.030 

0.027 

Subject #1 (A.R.) 

Without pilocarpine 

1 


— 

0.027 

1 



0.180 

Subject #2 (A.M.) 

Without pilocarpine 

2 

0.028 

0.038 

0.033 

2 

0.280 

0.360 

0.320 


* Iodine color test negative. 


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RECIPROCAL RELATIONSHIPS OF TIME AND TEMPERATURE 


329 


It was found that the water loss from the skin of a 
live pig does not differ significantly from that of one 
that is dead. In a cool environment the water loss 
per square centimeter per minute is approximate!}^ 
the same in man and pig. At higher environmental 
temperatures, the rate of water loss from human 
skin is tremendously augmented, whereas the corre- 
sponding increase in water loss from the skin of a pig 
is relatively small and is due to more rapid evapora- 
tion of tissue water rather than to sweating. 

17.5.3 Summary 

So far as can be judged by anatomic criteria the 
pig should be a suitable experimental subject from 
which to derive certain types of information regard- 
ing the effects of heat on human skin. Its various 
layers are of comparable thickness and structure. Its 
blood vessels are similar in size, number, and distri- 
bution. As vdW be shown later in Sections 17.6 and 
17.7, its susceptibility and reactions to control epi- 
sodes of hyperthermia are remarkably similar. 

Since a pig does not sweat, allowance should be 
made for the inability of porcine skin to lose heat 
through the vaporization of moisture derived from 
sweating. The significance of heat loss through vapor- 
ization of moisture in respect to cutaneous burning 
will be discussed in greater detail in Section 17.9. 

17.6 RECIPROCAL RELATIONSHIPS OF 
TIME AND TEMPERATURE^b 

The most direct mechanism by which exposure of 
the body surface to excessive heat results' in injury is 
the transfer of heat energy to the skin at so rapid a 
rate that its temperature is raised to a level incom- 
patible with cellular survival. Such localized thermal 
injuries are commonly referred to as burns. Although 
it is common knowledge that there is an inverse re- 
lationship between temperature and the amount of 
time required to produce a burn, there is remarkably 
little precise information regarding the rate at which 
burning occurs at any given temperature. 

Because of the experimental difficulties inherent in 
the making of accurate measurements of either the 
time or the temperature characteristics of thermal 
exposures so intense that they are capable of burning 
the skin in a fraction of a second, it was decided to 
establish by experimentation the reciprocal relation- 
ships of time and temperature necessary to destroy 
cells at lower temperatures and to extrapolate from 
these data the time curve that should represent the 


minimum cell-destroying exposures for higher de- 
grees of temperature. 

17.6.1 Method of Controlling Surface 
Temperature 

Direct exposure of the surface of the skin to a 
rapidly flowing stream of hot liquid was chosen as 
the method best adapted for the acquisition of these 
data. With this type of exposure, the surface of the 
skin could be maintained at the temperature desired 
without the establishment of an appreciable gradient 
between it and the source of heat. There was no in- 
sulation of the surface by a static layer of gas, liquid, 
or solid, no heat loss through vaporization of surface 
moisture, and no diminution of subsurface heat con- 
duction due to vascular occlusion by the application 
of pressure on the surface. The method was simple to 
operate and led to remarkably reproducible cutane- 
ous effects. 

The applicator by which a running stream of hot 
water was brought into direct contact with the skin 
consisted of a metal cup, the brim of which was cov- 
ered with a pad of closed-cell sponge rubber to insure 
a watertight contact. By means of an electric pump, 
water was circulated from a large constant-temper- 
ature reservoir through the cup, the open end of 
which was applied to the skin. The rate of flow was 
regulated by a screw clamp on the inlet tube and by 
the height of the outlet tube (see Figure 12). 



Tangential flow of a liquid produced no vertical 
component of force and thus no vertical pressure. 
Vertical water pressure within the cup could be var- 
ied between 70 and 86 cm of mercury by suitable 
adjustments of the aperture of the inlet and the 
height of the outlet tubes. A copper-constantan ther- 
mocouple measured the temperature of the water 
flowing next to the skin. During any period of ex- 
posure the temperature of the water flowing over the 
skin could be controlled to within 0.1 C. 


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330 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


Two methods were used to equilibrate the appara- 
tus before applying it to the skin. In one, the appa- 
ratus was applied to a block of linoleum, adjusted to 
the desired pressure, and transferred to the skin site 
to be exposed as soon as the temperature equilibrium 
was reached. In the other, the applicator was allowed 
to remain immersed in the hot water reservoir with 
the pump turned on until thermal equilibrium was 
established. The cup was then transferred immedi- 
ately to the skin and adjusted to the desired water 
pressure. 

Provision was made in the construction of this ap- 
paratus for studying the relation of the size of the 
area of exposure to the intensity of the resultant in- 
jury. This was accomplished by making the brim of 
the cup removable so that the area of skin to be ex- 
posed could be varied according to the aperture size 
of the brim selected for use. Thus, in the same region 
on the same animal and under identical conditions of 
time, temperature, and pressure, circular targets 
having a diameter of either 7 or 25 mm could be 
exposed. 

Individual burns in the animal experiments were 
25 mm in diameter. This was larger than desirable 
for human subjects and the diameter of the aperture 
of the cup was accordingly reduced to 7 mm for the 
human experiments. Before this was done, however, 
it was established by animal experimentation that 
the reduction in the size of the exposure area did not 
make any appreciable difference in the effect of such 
exposures on the epidermis. 

Water was employed as the source of hea t in all of 
the experiments summarized in Table 10. Because the 
question was raised as to whether or not a hypotonic 
fluid such as water might modify the effects of heat, 
a series of comparable exposures were made in which 
oil was substituted for water. There was no appre- 
ciable difference between the injury-producing po- 
tentiality of rapidly flowing streams of water and oil 
on either animal or human skin so long as the temper- 
ature and duration of exposure were the same. 

17.6.2 Experiments on Pigs 

The primary purpose of this investigation was to 
obtain information relating to the tolerance of hu- 
man skin to episodes of hyperthermia of varying 
duration and of varying degrees of intensity, and the 
direct approach would have been to make all experi- 
ments on human subjects. For various reasons, this 
was not feasible, and it was decided to acquire the 
basic data from experiments on pigs. From an ex- 


tensive series of observations on pigs, it was thought 
that a relatively small number of critical exposures 
of human skin would establish the extent to which 
the more comprehensive animal data were applicable 
to man. 

Closely clipped young (8 to 12 kg) white pigs were 
used. It was found that different portions of the body 
surface of the pig vary slightly in respect to their 
susceptibility to thermal injury. The largest uni- 
formly reacting area was the lateral body surface be- 
ginning in front of the thighs and extending forward 
over the shoulders. The skin of the neck and for 
about 10 cm to either side of the spine had a slightly 
higher thermal tolerance than that of the lateral body 
surface. The skin covering the thighs, the buttocks, 
the inguinal folds, and the mid-portion of the chest 
and abdomen had a slightly lower thermal tolerance. 

Results of experiments on pigs: The surface tem- 
perature, duration, and results of 179 hot water appli- 
cations to the lateral body surface of young white 
pigs are summarized in Table 10. 

The surface temperatures at which these exposures 
were made ranged between 44 and 100 C. The dura- 
tion of exposures varied between 1 second and 7 
hours. The majority of the exposed sites were kept 
under observation until the reaction had subsided or 
the lesion had healed. In the case of borderline re- 
actions duplicate exposures were made and excised 
at the end of 24 or 48 hours for microscopic study. 

As indicated in Table 10,’ a wide variety of reac- 
tions were observed. These ranged in severity from 
evanescent erythema to deep ulcers. 

In the beginning certain difficulties were encoun- 
tered in recognizing differences in the severity of cer- 
tain lesions. Although there was no difficulty in recog- 
nizing the difference between a reaction whose total 
effect was a mild and transient erythema and one 
that led to deep coagulative necrosis, it was not al- 
ways easy to recognize by clinical observations 
whether a given lesion represented a severe first- 
degree reaction with incomplete or focal epidermal 
destruction or a relatively mild second-degree re- 
action in which the epidermal destruction was com- 
plete. 

Apart from the microscopic appearance, the most 
reliable criteria by which to recognize transepidermal 
necrosis were (1) the ease with which dead but still 
intact epidermis could be displaced by friction on the 
second and third days after exposure, and (2) the de- 
velopment of complete encrustation of such a lesion 
within a week. 


SECRET 


RECIPROCAL RELATIONSHIPS OF TIME AND TEMPERATURE 


331 


sholds for thermal injury of porcine skin. 







Threshold 






Subthreshold 

and supra- 






exposures 

threshold 







exposures 






1® reactions 

2® and 3° 







reactions 






Focal 

Complete 





H3’'peremia epidermal 

epidermal 




No. 

only necrosis 

necrosis 

Temp 

Time 

of 


Seal- Small 

Red Pale 

C 

Min 

Sec 

expt Mild Severe ing ulcers 

burn burn 

52 


30 

1 

+ 





45 

1 


+ 

• 


1 

30 

1 



+ 


2 


4 



+ 


3 


1 



+ 

53 


20 

1 

+ 





30 

1 


+ 




45 

2 


+ 



1 


2 



+ 


1 

30 

3 



+ 


2 


1 



+ 

54 


15 

1 

+ 





25 

1 


+ 




35 

1 



+ 

55 


5 

1 

+ 





10 

1 






15 

1 

+ 





20 

1 


+ 




25 

1 



+ 



30 

3 



+ 

56 


10 

1 


+ 




15 

1 



+ 



20 

1 




58 


5 

1 

+ 





10 

1 



+ 

60 


2 

1 

+ 





2 

1 


+ 




3 

1 


+ 




5 

1 



+ 



7 

1 


+ 




7 

1 



+ 

. 


10 

2 



+ 


10 


1 



+ 

65 


1 


+ 





2 

1 



+ 



3 

1 



+ 


10 


1 



+ 

70 


1 

2 



+ 



2 

1 



+ 


3 


2 



+ 

75 


1 

1 



+ 



5 

1 



-b 

80 


1 

1 



+ 



5 

1 



+ 

85 


1 

1 



+ 



5 

1 



+ 

90 


1 

1 



+ 



5 

1 



+ 

95 


1 

1 



+ 



3 

1 



+ 

100 


1 

1 



+ 



3 

1 



+ 


Temp Time 
C Min Sec 


Subthreshold 

exposures 

1° reactions 

Focal 

Hyperemia epidermal 
No. only necrosis 
of . Seal- Small 

expt Mild Severe ing ulcers 


Threshold 
and supra- 
threshold 
exposures 
2° and 3° 
reactions 
Complete 
epidermal 
necrosis 
Red Pale 
burn burn 


44 

420 


1 



+ 



45 

150 


1 

+ 






180 


1 





+ 

46 

45 


1 







60 


1 


+ 





90 


1 





+ 

46.5 

45 


1 

+ 






60 


1 





+ 

47 

35 


1 

+ 






45 


1 





+ 


50 


1 





+ 


60 


1 





+ 

48 

10 


3 

+ 






12 


1 


+ 





14 


2 



+ 




14 


1 





+ 


15 


2 





+ 


16 


1 


+ 





18 


1 





+ 


20 


1 





+ 

49 

3 



+ 






4 


5 

+ 






5 


2 







6 


5 


+ 





6 


2 



+ 




6 


2 




+ 



7 


2 


+ 





7 


1 



+ 




7 


1 




+ 



8 


4 



+ 




8 


1 




+ 



8 


2 





© 


9 


11 





+ 


10 


5 





+ 

50 

1 


1 

+ 






2 


1 

+ 






4 


1 



+ 




5 


1 


+ 





5 


3 



+ 




5 


2 




+ 



5 


2 





+ 


6 


2 





+ 


6 

30 

2 





+ 

51 


45 

2 

+ 






1 


2 

+ 






1 

30 

2 

+ 






2 


1 



+ 




3 


2 


+ 





3 


2 


+ 





3 


2 





+ 


4 


2 





+ 


5 


1 




+ 



5 


1 





+ 


10 


2 





+ 


SECRET 


332 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 



LEFT SIDE 



Figure 13. Photograph of right and left sides of pig with temperature and duration of each exposure indicated. Lesions 
on right side were 24 hours old and those on left side 7 days old. 


All exposures sufficient to cause vascular reaction 
but insufficient to destroy the full thickness of the 
epidermis throughout the entire target area were 
designated as sub threshold . The entire range of cu- 
taneous responses to subthreshold exposures were 
characterized as first-degree reactions. The shortest 
time at any given temperature that was capable of 
causing transepidermal necrosis constituted a thresh- 
old exposure. The effect of a threshold exposure on 
the skin was characterized as a second-degree re- 
action. All exposures which were of longer duration 
or higher temperature than was necessary to cause 
complete epidermal destruction were designated as 
suprathreshold and their effects as third-degree re- 
actions. 

The macroscopic appearance of different degrees of 
cutaneous reaction to hyperthermia may be seen in 
the photographs of the right and left sides of pig 924 


shown in Figure 13. At the time the photographs 
were made, the lesions on the right side were 24 hours 
old and those on the left were 7 days old. It is ap- 
parent from these photographs that the duration of 
exposure at any given temperature was remarkably 
critical in relation to the kind of reaction evoked. It 
is equally apparent that the time required to produce 
a given degree of reaction varied inversely with the 
temperature. 

17.6.3 Experiments on Human Subjects 
In order to determine the extent to which the re- 
ciprocal relationships of time and temperature in the 
production of cutaneous burns in pigs were applicable 
to human skin, a series of exposures similar to those 
described on pigs were made on human subjects. 
Some were made to the skin of the anterior thoracic 
region and others on the ventral aspect of the fore- 


SECRET 




RECIPROCAL RELATIONSHIPS OF TIME AND TEMPERATURE 


333 


arm. The applications were made with the apparatus 
shown in Figure 12. 

As in the case of the pig experiments, three de- 
grees of skin reaction were observed. Reactions char- 
acterized as first-degree were those that fell short of 
complete destruction of the epidermis. At one ex- 
treme a first-degree reaction consisted of a faint and 
transient erythema. At the other, extreme erythema 
was severe and prolonged and miliary vesicles formed 
but failed to coalesce. Lesions in which there was 
complete destruction of the epidermis over the entire 
target area were designated second- or third-degree 
reactions, depending on the extent to which the 
dermis was involved. As in the case of the pig, a 
threshold exposure represented the shortest time at 
any given temperature that caused complete de- 
struction of the epidermis. 

That a given exposure of human skin had resulted 
in transepidermal necrosis was usually but not al- 
ways recognized by complete vesication of the target 
area. Although vesication resulting from heat indi- 
cates that the full thickness of the epidermis has been 
destroyed, absence of vesication does not necessarily 
indicate that the epidermis has escaped complete 
destruction. Transepidermal necrosis without vesica- 
tion was observed after certain suprathreshold ex- 
posures. The explanation of this phenomenon will be 
discussed in Section 17.8.8. 

The results of the human experiments have been 
summarized in Table 1 1 . 

17.6.4 Relative Vulnerability of Porcine 
and Human Skin to Thermal Injury 

To facilitate comparison of the data included in 
Tables 10 and 11, certain ot the more critical observa- 
tions have been depicted graphically in Figure 14. 
The solid line was established by points representing 
the time and temperature of exposures that caused 
minimal second-degree reactions of porcine skin. The 
points by which this line was established are repre- 
sented by crosses. Each cross represents the shortest 
time at the temperature indicated that resulted in 
transepidermal necrosis of the entire target area. The 
more that the time of any given exposure placed it to 
the right or that the temperature of any given ex- 
posure placed it above the solid line, the greater the 
depth to which the skin was destroyed. All exposures 
that were situated a significant distance above and to 
the right of the solid line were suprathreshold and all 
those situated a significant distance below and to the 


Table 11. Time-surface temperature thresholds for 
thermal injury of human skin. 


Threshold 
Sub- and supra- 
threshold threshold 


exposures exposures 




1° reac- 

2° and 3° 

Temp 


tions 

reactions 

at 

Duration 

Hyperemia 


sur- 

of 

without 

Complete 

face 

exposure 

loss of 

epidermal Sub- 


No. C Hr Min Sec epidermis necrosis ject Date 


1 

44 

5 



+ 


BF 

2/6 

2 * 


5 



+ 


BF 

2/23 

3 


6 




+ 

BF 

2/6 

4* 


6 




+ 

BF 

2/23 

5* 

45 

2 



’+ 

+ 

KL 

2/16 

6* 


3 





KL 

2/3 

7 


3 




+ 

HA 

2/4 

8* 

47 


18 



+ 

RKt 

2/13 

9* 



20 



+ 

KL 

2/25 

10* 



20 


+ 


AM 

2/26 

11* 



20 


+ 


PG 

2/26 

12 



25 



+ 

RKt 

1/8 

13* 



40 



+ 

AM 

2/26 

14 



40 



+ 

PG 

2/26 

15 



45 



+ 

RKt 

1/8 

16 

48 


15 


+ 


PG 

7/19 

17 



15 



+ 

AR 

7/19 

18 



18 



+ 

AM 

6/26 

19* 

49 


8 


+ 


AM 

2/16 

20 



8 


+ 


AM 

6/26 

21 



9 

30 


+ 

AM 

6/26 

22* 



10 



+ 

AM 

6/26 

23 



11 



+ 

AM 

6/26 

24 



15 



+ 

AM 

6/26 

25 

51 


2 


+ 


AM 

6/26 

26 



4 



+ 

AM 

6/26 

27 



6 



+ 

AM 

6/26 

28 

53 



30 

+ 


AM 

6/26 

29 



1 

30 


+ 

AM 

6/26 

30 

55 



20 

’+ 


PG 

7/19 

31 




30 


+ 

AR 

7/19 

32* 

60 



3 

+ 


FH 

2/1 

33* 




5 


+ 

FH 

2/1 


* Oil used instead of water as source of heat. 


t Subject RK was atypical in that his threshold for thermal injury was 
significantly lower than that of other experimental subjects. 


left of the solid line were subthreshold. The range of 
variation is shown in Table 10. 

The extent to which the results of human exposure 
corresponded with those of the more comprehensive 
animal experiments is indicated by the open and solid 
circles in Figure 14. The open circles represent the 
maximum exposure at the temperature indicated 
that failed to destroy human epidermis and the 
closed circles represent the minimum time at the 
temperature indicated that resulted in complete 
destruction of human epidermis. 

The broken line in Figure 14 represents the ap- 
proximate threshold at which the first morphological 


SECRET 


334 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


SECONDS MINUTES HOURS 



Figure 14. Graph showing thresholds for porcine skin 
at which microscopic evidence of spidermal injury is 
first apparent (broken line) and at which transepidermal 
necrosis is complete (solid line). Crosses indicate criti- 
cal individual experiments and show shortest time at 
temperature indicated at which transepidermal necrosis 
of entire target area occurred. Open and solid cir- 
cles show effects of heat on human skin. Open circles 
represent longest exposure at temperature indicated 
that failed to destroy epidermis. Solid circles repre- 
sent shortest exposure at temperature indicated that re- 
sulted in transepidermal necrosis. 


evidence of thermal damage to porcine epidermis was 
recognized. Exposures situated below the broken line 
caused no appreciable change in the microscopic ap- 
pearance of the epidermis. Exposures lying between 
the broken and solid lines resulted in varying de- 
grees of epidermal damage short of transepidermal 
neciosis. Since the reactions of human skin to con- 
trol episodes of hyperthermia were not examined 
microscopically, no inferences can be drawn as to the 
reciprocal relations of time and temperature at 
which microscopic evidence of injury to human epi- 
dermis was first recognizable. 


17.6.5 Mathematical Predictability of 
Epidermal Destruction by Exposure to HeaU^ 
From a kinetic standpoint, the reciprocal relation- 
ships of time and temperature in the production of 
transepidermal necrosis follow the general pattern of 
rate processes. If the reaction leading to thermal 
death of epithelium conforms to that of most physical 
and chemical rate processes, it should be quanti- 
tatively predictable by the following equation: 

^ - ^E/R{Tt + 273 ) 

dt 

where d^/dt is the rate at which an arbitrary function 


^ By F. C. Henriques, Jr. 


of epidermal injury 12 as determined by histological 
examination is produced. Tt is the temperature in C 
at the time, t, at the basal epidermal layer; R is the 
gas constant and is equal to 2 calories per C per mole; 
and both A and AE are constants evaluated from the 
experimental data. 

Equation (7) can also be expressed as an integral 
equation, namely 

t 

12 = A 

0 

where if T t, the dependence of the basal epidermal 
temperature on time, is known the integral can be 
evaluated. 

In all cases where the temperature* of the basal 
layer of epidermis can be considered as independent 
of time of heat exposure, equation (8) can be inte- 
grated to equation (9). 

12 = ^g-A^/fi(T + 273)^^ (9) 

An examination of the transepidermal threshold 
data depicted in Figure 14 and the epidermal time- 
temperature data given in Table 7 (Section 17.3.2) 
and illustrated in Figure 15 shows that equation (9) 
is applicable in all heat exposures where the skin 
surface temperature is less than 50 C; furthermore 
the skin surface temperature can be substituted for 
the steady-state basal epidermal temperature since 
the differences (<0.3 C) between these two values 
are negligible in this temperature range. 

Thus, by using equation (9) in this temperature 
range, it is possible to evaluate numerically A and 
AE by standard graphical procedures from the data 
for the threshold of complete transepidermal necro- 
sis; and the following equations are obtained. 

AE = 150,000 cal/mole (10) 

and 

A = 3.1 X 109»sec-b (11) 

This value of A depends upon the arbitrary choice 
of the value of unity for fi. Thus, when the threshold 
of complete epidermal necrosis is reached. 


/ 


272) 


(8) 


= 1 . ( 12 ) 

By again making use of equation (9) a similar 
analysis can be made of the time-temperature rela- 
tionship depicted by the broken line of Figure 14. 
Since these data are not so complete as those used 
above, it is best to use the same numerical values 
given by equations (10) and (11) for and A, and 
solve for the numerical value of 12. 

These data are found to be best represented by 
12 = 0.53 (13) 


SECRET 


RECIPROCAL RELATIONSHIPS OF TIME AND TEMPERATURE 


335 


when the upper limit of exposure which can be toler- 
ated without the occurrence of transepidermal ne- 
crosis is reached. 

Although the values given by equations (10) to 
(13) for A, AE, and 12 were obtained through the use 
of equation (9), which requires that the epidermal 
temperature can be considered constant during the 
entire heat exposure, these numerical values should 
permit the computation of the two thresholds of 
transepidermal injury under all conditions by means 
of equation (8), so long as Tt is known. 

Under the experimental conditions that the data 
depicted in Figure 14 were obtained, namely, con- 
stant skin surface temperature during the entire heat 
exposure, it is possible to ascertain the time de- 
pendence of basal epidermal temperature by means 
of equation (6c). Referring to equation (6c), it is 
found that the evaluation of Tt depends upon two 
parameters. To and y. An examination of the equa- 
tion shows that Tt is very insensitive to variations in 
To, the original epidermal temperature ; 35 C is taken 
as the original skin surface temperature (see Table 6 
of Section 17.3.2). 

In view of the uncertainties which enter into this 
direct experimental evaluation of y by means of 
equation (6b), it is best to evaluate it empirically by 
obtaining the best fit to the complete transepidermal 
necrosis data. 

It is then found that 

y = 0.15 (14) 

if t, the time during the heat exposure, is expressed 
in seconds. This numerical value checks well with 
that obtained by direct substitution of the experi- 
mental values for the thermal conductivity, heat 
capacity, density, and thickness of epidermis (see 
Section 17.3.2) into equation (6b). 

A consideration of equations (6a), (6c), and (8) 
together with the requisite numerical values given by 
equations (10), (11), and (14) shows that the experi- 
mental data given in Table 10 and depicted in Fig- 
ure 14 are completely described by the following 
equation : 

t 

ft = 3.1 X lO"* + (15) 

0 

where 


0.15/Vi 



where is the degree of injury to be expected, Tg is 


the surface temperature of the skin during heat ex- 
posure, Tt is the temperature of the basal epidermal 
layer after the time t in seconds has elapsed, and the 
numerical values of the integral of equation (15a) as 
a function of 0.15/V^ are tabulated.^® 

For 12 > 0.5 and < 50 C the time dependence 
of Tt can be ignored and Tt put equal to Tg; equa- 
tion (15) can then be integrated and takes the form 
of equation (9), which greatly facilitates the compu- 
tation of For all > 50 C and 12 < 1, the time 
dependence of T < cannot be neglected, and the evalu- 
ation of 12 by means of equation (15) requires one of 
the standard methods of numerical integration.^’ 

This numerical determination of 12 from the two 
experimental parameters, t and Tg, permits the pre- 
diction of the degree of epidermal injury, since an 
12 < 0.53 results in a time- temperature relationship 
that can be tolerated without the occurrence of 
transepidermal necrosis, and 12 > 1.0 results in a 
time-temperature relationship which produces com- 
plete epidermal necrosis. 

The success of equations (15) and (15a) in predict- 
ing these time-temperature relationships is shown in 
Table 12. 

It can be seen that the agreement of the experi- 
mental data of Section 17.6.3 with this equation is, 
in general, excellent, and, thus, that the tacit assump- 
tion throughout this section of the applicability of 
equation (7) is justified. In the four cases where there 
is appreciable variance between experiment and 
prediction, either the experimental data are in- 
sufficient or the duration of heat exposure was too 
short to preclude considerable experimental error. 
Thus, equations (15) and (15a) probably give a more 
accurate prediction of epidermal injury thresholds 
than the dotted and solid lines of Figure 14. 

The numerical computations resulting from equa- 
tion (9) are also included for comparative purposes. 
For the reasons stated above there is no appreciable 
difference, under these specific experimental condi- 
tions, between this equation and equation (15) for all 
surface temperatures below 50 C. Equation (9) cor- 
responds to an experimental condition in which the 
basal epidermal layer is immediately brought to and 
maintained at a constant temperature. If this were 
feasible at 70 C, complete epidermal necrosis would 
result in 3 ten-thousandths of a second. The 2,000- 
fold difference between this value and 0.5 second 
predicted by equations (15) and (15a) indicate the 
extreme importance of the heat capacity of the skin 
during the early period of heat exposure. 


SECRET 


336 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


Table 12. A comparison of the experimental time-temperature relationship for transepidermal injury as depicted by 
Figure 14 with those obtained from equations (9) and (15). 


Minimum time in seconds for complete 
transepidermal necrosis 
12 = 1 


Experimental 

Equation Equation solid line 

(9)* (15) Figure 14 


Surface 

temp 

C 


Maximum time in seconds for subthreshold 
transepidermal necrosis 
12 = 0.53 

Experimental 

dotted line Equation Equation 

Figure 14 (15) (9)* 


23,000 

23,000 

25,000 

44 

18,000t 

12,000 

12,000 

11,000 

11,000 

11,000 

45 

7,200t 

5,900 

5,800 

5,100 

5,200 

5,000 

46 

3,000 

2,800 

2,700 

2,400 

2,500 

2,400 

47 

1,300 

1,380 

1,300 

1,100 

1,200 

1,100 

48 

560 

650 

600 

580 

630 

570 

49 

260 

340 

310 

270 

325 

300 

50 

130 

165 

140 

130 

165 

160 

51 

75 

90 

68 

65 

91 

90 

52 

44 

52 

35 

16 

31 

35 

54 

18 

19 

8 

4.4 

13 

16 

56 

8.3 

8.1 

2.3 

0.25 

3.0 

5 

60 

2.6 

2.3 

0.13 

0.009 

1.0 

2t 

65 

1.0 

0.7 

0.005 

0.0003 

0.5 

It 

70 


0.4 

0.0002 


* Above 50 C equation (9) has no experimental significance, 
t Experimental value uncertain. 


These tabulated values, resulting from the solution 
of equation (15), are of course only valid under spe- 
cific experimental conditions, namely, only when the 
skin surface temperature is immediately brought to 
and maintained at a constant value during the entire 
heat exposure. However, equation (15) should ac- 
curately predict the epidermal injury to be expected 
from all conceivable kinds of heat exposures, so long 
as the temperature dependence of the skin surface 
temperature as a function of time is known, since the 
time-temperature relationship at the basal epidermal 
layer can be predicted quite accurately by making 
use of the “infinite body’’ heat theory implicit in 
equation (15a). (See Section 17.3.1.) 

17.6.6 Vulnerability of Ischemic Skin to 
Thermal Injury 

One of the reasons that a running stream of hot 
water was employed as the source of heat in these ex- 
periments was that by this technique there would be 
no mechanical interference with the circulation of 
blood through the dermal capillaries. The exposures 
were made at atmospheric pressure. It was felt that 
circulation of relatively cool blood through the der- 
mal capillaries would probably tend to protect the 
skin against burning and that any method employed 
for the production of uniform burns should be one 
which did not cause mechanical interference with 
capillary circulation. 

The following experiments were undertaken for the 


purpose of determining the extent to which local im- 
pairment in blood flow may increase the vulnerability 
of the epidermis to thermal injury. 

A control series of burns were made on each of 
three pigs by exposing various skin sites to hot water 
at atmospheric pressure. The predetermined time and 
temperature of each exposure were such that severe 
first-degree or mild second-degree reactions could be 
anticipated. See Table 13. 


Table 13. Effects of thermal exposures with and without 
pressure ischemia. 


Ani- 

mal 

num- 

ber 

Expt 

temp 

C 

Expo- Excess 
sure pres- 

dura- sure 
tion on skin 
(min) (mm Hg) 

No. of 
exp 
made 

Number of lesions 
Without With 
transepi- transepi- 
dermal dermal 
necrosis necrosis 

887 

49 

7 

0 

5 

5 

0 


49 

9 

0 

5 

0 

5 


49 

7 

80 

5 

5 

0 

899 

49 

7 

0 

4 

4 

0 


49 

8 

0 

4 

2 

2 


49 

9 

0 

4 

0 

4 


49 

7 

80 

4 

4 

0 


49 

8 

80 

4 

3 

1 

901 

51 

2 

0 

3 

3 

0 


51 

3 

0 

3 

2 

1 


51 

4 

0 

3 

0 

3 


51 

2 

80 

3 

3 

0 


51 

3 

80 

3 

1 

2 


It was found that all 7-minute exposures at 49 C 
and all 2-minute exposures at 51 C made at atmos- 
pheric pressure were subthreshold in the sense that 


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RECIPROCAL RELATIONSHIPS OF TIME AND TEMPERATURE 


337 


they failed to cause complete transepidermal ne- 
crosis. That they were close to threshold was indi- 
cated by the fact that all 9-minute exposures at 49 C 
and all 4-minute exposures at 51 C did cause trans- 
epidermal necrosis. 

After it was established that the position of the 
threshold for transepidermal necrosis in these ani- 
mals was between 7 and 9 minutes at 49 C and be- 
tween 2 and 4 minutes at 51 C for exposures made at 
atmospheric pressure, a second series of exposures 
were now made during which the water pressure was 
increased by an amount corresponding to 80 mm of 
mercury. With this amount of pressure on the sur- 
face of the skin during the time that it was exposed 
to heat, there was no instance in which the reaction 
to a 7-minute exposure at 49 C or to a 2-minute ex- 
posure at 51 C was increased in severity. 

It is apparent from the data summarized in 
Table 13 that the application of pressure sufficient 
to collapse superficial dermal capillaries during a 
period of exposure does not cause appreciable aug- 
mentation in the vulnerability of epidermis to ther- 
mal injury. 

In view of the extreme thinness of the epidermis, 
these results were to be expected, since, for reasons 
given in Section 17.3.2, the epidermal temperature is 
primarily determined by the skin surface tempera- 
ture. Thus the dermal temperature gradients, which 
may be appreciably altered in ischemic as compared 
with normal skin during thermal exposure, would 
have little effect on the time-temperature relation- 
ship that exists at the epidermal-dermal interface. 

17.6.7 Latent Thermal Injury and Cumulative 
Effects of Repeated Subthreshold Exposures 

If the data summarized graphically in Figure 14 
are recalled it is apparent that recognizable damage 
to the epidermis occurred only during the terminal 
phase of the subthreshold exposures represented in 
these experiments. Not until the duration of any 
given episode of hyperthermia was such as to bring 
it to the level indicated by the interrupted line in 
Figure 14 was there recognizable evidence of epi- 
dermal injury. This phenomenon is even more readily 
apparent in the photographs shown in Figure 13. 
In these, it may be seen that the 7-minute exposure 
at 49 C on the left side of the animal shows only a 
trace of residual erythema, whereas both of the sites 
of 9-minute exposures at that temperature show 
transepidermal necrosis. 

Does this indicate that no epidermal injury had 


been sustained during the first 7 minutes, or does it 
mean that injury was present but morphologically 
latent? 

In order to gain more information concerning this 
point, the experiments summarized in Table 14 were 
undertaken. Thermal exposures were made with a 
running stream of hot water at 49 C and at atmos- 
pheric pressure. Three young pigs were used. 

The first series of exposures (1 to 18) were for con- 
trol purposes and served to establish the reproduci- 
bility of reactions to single exposures at this temper- 
ature. It may be seen that there was not a single in- 
stance in which an exposure for less than 7 minutes 
caused recognizable necrosis of the epidermis and 
that in every instance in which exposures as long as 
9 minutes were given, there was complete necrosis of 
the epidermis. Skin sites receiving 7-minute expo- 
sures recovered without loss of epidermis, whereas 
skin sites receiving 9-minute exposures underwent 
complete ulceration. 

The control exposures were followed by a series 
(19 to 39) in which repeated exposures, individually 
incapable of causing recognizable epidermal injury, 
were applied to the same area. It was found, for in- 
stance, that, although a single 3-minute exposure at 
49 C caused no recognizable change in the epithelial 
cells, three such exposures separated by recovery 
periods as long as 24 minutes had the same total de- 
structive capacity as a single continuous 9-minute 
exposure. 

It was clear that a certain amount of epidermal in- 
jury was sustained during the first 3 minutes and 
that at least 24 minutes were required before there 
was an appreciable recovery from this injury. That 
complete recovery occurred alter between 2 and 
4 hours was indicated by experiments 30 and 31. 

Experiments 34 to 39 showed what might have 
been expected, namely, that recovery from the latent 
injury of a 2-minute exposure was more rapid and 
that from a 5-minute exposure less rapid than was 
the case after a 3 -minute exposure. 

Further discussion of the implications of these ex- 
perimental results will be found in Section 17.8 of 
this chapter. 

17.6.8 Summary 

The reciprocal relationships of time and temper- 
ature in the causation of transepidermal necrosis are 
similar for similar skin areas of man and pig. 

Thermal injury or burning of the skin was ob- 
served to occur at surface temperatures as low as 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


Table 14. The cumulative effects of repeated sub threshold thermal exposures on the skin of the pig. 
All exposures were made to water at 49 C. 


Duration 
of each 
exposure 
(min) 

No. of 
exposures at 
same site 

Interval 

between 

exposures 

Effect of exposure on skin 

No evidence of 

epidermal injury Epidermal necrosis 

Mild ^vere Complete 

vase. vase. and 

reaction reaction Focal irreversible 

Expt 

No. 

3 

1 


+ 


.. 


1 


1 


+ 




2 


1 


+ 




3 

4 

1 


+ 




4 

5 

1 


+ 




5 

6 

1 



+ 



6 


1 



+ 



7 


1 



+ 



8 

7 

1 



+ 



9 


1 




+ 


10 

8 

1 




+ 


11 


1 




+ 


12 


1 





+ 

13 

9 

1 





+ 

14 


1 





4- 

15 


1 





-h 

16 


1 





+ 

17 


1 





+ 

18 

3 

3 

3 min 




+ 

19 


3 

3 min 





20 


3 

3 min 




+ 

21 

3 

3 

6 min 




+ 

22 

3 

3 

12 min 




+ 

23 

3 

3 

24 min 




+ 

24 

3 

3 

48 min 




+ 

25 


3 

48 min 



-h 


26 

3 

3 

72 min 



+ 


27 


3 

72 min 



+ 


28 

3 

3 

96 min 



+ 


29 

3 

3 

120 min 


+ 



30 

3 

3 

240 min 

+ 




31 

3 

3 

24 hr 

+ 




32 

3 

3 

48 hr 

+ 




33 

2 

5 

2 min 




+ 

34 


5 

30 min 

+ 




35 


5 

60 min 

+ 




36 

3 

2 

12 min 


+ 



37 

5 

2 

60 min 




'+ 

38 


2 

240 min 



+ 


39 


44 C and it can be inferred from the shape of the 
time-temperature curve that the threshold at which 
hyperthermal cellular injury is first sustained is not 
far above the level that is normal for the blood. 

The rate at which injury occurs increases rapidly 
if the temperature is raised. The progress of injury 
at any given temperature is determined by the dura- 
tion of the hyperthermic episode. Thus, the amount 
of time required to convert a reversible into an irre- 
versible cellular injury is different for each degree of 
temperature and in the case of the epidermis can be 
computed if the surface temperature as a function of 
time is known. 


The existence of latent or morphologically unrecog- 
nizable cellular injury after certain apparently harm- 
less thermal exposures and the fact that the time re- 
quired for recovery from such latent injuries becomes 
longer the nearer they approach the threshold of 
microscopic visibility were demonstrated experi- 
mentally. 

17.7 PATHOLOGY OF CUTANEOUS 
BURNS AND THEIR PATHOGENESIS 

In the foregoing section, measurements of the re- 
ciprocal relationships of time and surface tempera- 
ture with respect to the capacity of thermal exposures 


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339 


to destroy the epidermis were reported. The following 
studies concern the pathological characteristics of 
cutaneous injuries caused by thermal exposures at 
different temperatures and for different durations, 
and a comparison of the pathogenesis of cutaneous 
burns in man and pig. 

17.7.1 Experimental Procedure 

Much of the material used in this investigation 
was derived from the experiments described in Sec- 
tion 17.6 of this chapter. It was added to from sev- 
eral sources (see Table 15). Since most of the lesions 
produced in the experiments reported in Section 17.6 
were not excised until they had been under clinical 
observation for days or weeks, many duplicate ex- 
posures were made and excised in order to observe in 
the various types of lesions the sequence of micro- 
scopic changes that took place between injury and 
repair. To acquire this material, approximately 60 
additional hot water exposures of pigs were made and 
examined microscopically after recovery periods 
ranging between a few seconds and several weeks. 
Additional material comprised a series of burns of 
porcine skin made by exposure to hot air at temper- 
atures varying between 80 and 900 C. There were 
two series of human burns, one comprising 33 experi- 
mentally produced lesions which were studied clini- 
cally but were not excised for microscopic examina- 
tion, and the other comprising a collection of skin 
specimens obtained after death from victims of con- 
flagrations. 

Sections of tissue for microscopic examination were 
cut from specimens that had been fixed in Zenker- 
formol or 10 per cent formaldehyde. Phloxine- 
methylene blue stains were made routinely and were 
augmented by sections stained with hemotoxylin and 
eosin or by Poliak’s modification of Masson’s tri- 
chrome method. Many sections were stained by the 
Feulgen technique. 


Table 15. Sources and kinds of material used for study 
of the pathogenesis of cutaneous burns. 


Sub- 

ject 

Source 

of 

heat 

Range 

of 

temp 

C 

Range of 
exposure 

Range of 
recovery 
period 

Pig 

Water 

44-100 

0.5 sec -7.5 hr 

1 min-4 weeks 

Pig 

Air 

80-900 

0.5 min-45 min 

1 min-3 days 

Man* 

Water 

44-60 

3 sec-6 hr 

1 min-4 weeks 


or oil 




Man 

Air 

? 

? 

Less than 1 hr 


* Lesions not excised for microscopic study. 


17.7.2 General Consideration of Quantitative 
and Qualitative Effects of Heat on Skin 

A cutaneous injury caused by hyperthermia may 
be characterized quantitatively according to the 
depth to which the tissue has been destroyed, or qual- 
itatively according to the nature of the changes that 
have occurred. The characterization in Section 17.6 
of hyperthermic episodes as subthreshold, threshold, 
and suprathreshold referred to their quantitative 
capacities for injury production, the determining 
factor being the capacity of the exposure to cause 
complete destruction of the epidermis. 

Thus, any exposure that failed to cause complete 
destruction of the epidermis was designated as sub- 
threshold and any reaction short of transepidermal 
necrosis was one of the first-degree. A second-degree 
reaction was one caused by the shortest exposure at 
any given temperature, or by the lowest temperature 
at any given time, that resulted in full-thickness de- 
struction of the epidermis. Although it was not pos- 
sible to destroy the entire thickness of the epidermis 
without some damage to the underlying connective 
tissue, dermal necrosis was a relatively insignificant 
feature of a truly threshold exposure. A third-degree 
reaction was one caused by an exposure that was 
suprathreshold in respect to time or temperature 
and was accordingly one in which a significant degree 
of dermal necrosis usually accompanied the destruc- 
tion of the epidermis. 

Slope of Transcutaneous Temperature Gradi- 
ent IN Relation to Depth and Quality of Burn 

If account is taken of the potential variations in 
the intensity and duration of the different thermal 
exposures that are capable of producing burns of 
similar depth, it becomes apparent why thermal 
lesions of approximately the same depth may be 
qualitatively dissimilar. ^ 

This fact is more readily appreciated by reference 
to Figures 15 and 16. The critical temperature, so far 
as the ultimate fate of the epidermis is concerned, is 
that attained at the interface between epidermis and 
dermis rather than that of the surface. In Figure 15 
are shown the estimated changes® in temperature 
that would occur at the basal cell level during the 
course of thermal exposures at three different surface 
temperatures if each were terminated at a time calcu- 
lated to be just adequate to destroy the epidermis. In 
Figure 16 are shown the temperatures that would 

® Calculations based on data presented in Section 17.3. 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


100 

90 

8 0 

7 0 

6 0 




Figure 15. Curves depicting changes in temperature 
at interface between dermis and epidermis during sur- 
face exposures of 45 (A), 55 (B), and 100 (C) C. Each 
of these was threshold exposure in that 3 hours, 0.4 
minute, and 0.1 second, respectively, are estimated to 
be shortest time at indicated temperature that would 
cause transepidermal necrosis. (Estimates derived 
from measurements reported in Section 17.3.2.) 



Depth in mm 

Figure 16. Solid line traversing each chart from left to 
right depicts temperature gradient through first 2 mm of 
skin at conclusion of exposures estimated to be just 
sufficient to cause transepidermal necrosis. Inter- 
rupted line traversing each chart from left to right de- 
picts original pre-exposure temperature gradient 
through skin to depth of 2 mm. The 0 vertical line in 
each represents surface of skin. Interrupted vertical 
line at depth of approximately 0.1 mm indicates depth 
of dermal-epidermal interface. In A, surface tempera- 
ture of 45 C had been maintained for 3 hours. In B, 
surface temperature of 55 C had been maintained for 
0.4 minute. In C, surface temperature had been 
maintained at 100 C for 0.1 second. (Estimates de- 
rived from measurements reported in Section 17.3.2.) 


prevail at different depths below the surface of each 
at the moment that the duration of the exposure was 
just sufficient to cause irreversible injury of the en- 
tire thickness of the epidermis. 

In each instance, the effects would be quantita- 
tively similar, in that irreversible cellular injury 


would extend to, but not far beyond, the basal cell 
layer. That qualitative differences in the resulting 
reactions might exist despite their quantitative simi- 
larity can be inferred from the fact that in the ex- 
posure shown in Figure 15A the epidermis was de- 
stroyed by a 3-hour episode of hyperthermia the in- 
tensity of which at no time rose above 44.8 C at the 
basal cell level. Approximately the same amount of 
irreversible change would be sustained as the result 
of the exposure depicted in 15 C. In the latter in- 
stance, the epidermis was destroyed in approxi- 
mately 0.1 second by an episode of hyperthermia in 
which the temperature at the basal cell level rose 
sharply and briefly to 70 C. The exposure depicted 
in 15B falls about midway between these extremes. 
Although the total amount of irreversible injury is 
about the same in each, it is not surprising that the 
three lesions produced in this manner differed quali- 
tatively. 

Since certain qualitative characteristics of thermal 
reactions are dependent on the degree to which the 
temperature of the tissue has been raised, it follows 
that the longer any given episode of tissue hyper- 
thermia is maintained, the greater the likelihood that 
the qualitative attributes of the reaction will reflect 
the intensity of the exposure. 

Such was found to be true : The more severe the ex- 
posure, the greater were the qualitative differences 
between the reactions produced at high and low sur- 
face temperatures. 

An additional reason for the occurrence of quali- 
tative differences in quantitatively similar reactions 
to thermal exposures of different intensity is shown 
in Figure 16. There are depicted the calculated trans- 
cutaneous thermal gradients to a depth of 2 mm that 
would exist at the moment of completion of the same 
three episodes of hyperthermia illustrated in Fig- 
ure 15. In each instance, irreversible thermal injury 
would extend to, but not appreciably beyond, the 
basal cell layer. In the exposure depicted in A (Fig- 
ure 16), the temperature of the dermis to a depth of 
about 2 mm was elevated above normal for at least 
2 hours. In the exposure depicted in C, the transcu- 
taneous thermal gradient was so steep that the re- 
sulting temperature changes in the dermis were ex- 
ceedingly brief and superficial. It is apparent why the 
epithelial cells would be destroyed in C with rela- 
tively little disturbance of the dermis, whereas, in A, 
the same or even a lesser degree of epidermal injury 
might be accompanied by a severe and persistent 
vascular disturbance. 


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341 


17.7.3 First-Degree Reactions 

Hyperemia, Edema, and Cyanosis 

Sufficient dilatation of the superficial capillaries to 
cause erythema characteristically accompanied and 
frequently preceded damage to the epithelium. One 
exception to this generalization represented in the 
material upon which this investigation was made was 
provided by the effects of heat on the skin of animals 
suffering from circulatory failure. In the presence of 
circulatory failure, there was frequently such a pro- 
found depression of vasomotor irritability that injuri- 
ous episodes of either high- or low-intensity hyper- 
thermia failed to elicit vascular reactions even though 
extensive epidermal injury was sustained. Other cir- 
cumstances in which thermal damage of the epider- 
mis was sustained with little or no accompanying 
vascular reaction included exposures of sufficient in- 
tensity to burn the stratum corneum, but so brief as 
to cause little or no rise in dermal temperature. 

Attention has already been called to the fact that 
the duration of an episode of low-intensity hyper- 
thermia must be greatly prolonged if it is to produce 
an injury quantitatively comparable to one resulting 
from a high-intensity exposure. Since the dermal 
blood vessels are far more responsive to temperature 
changes than are the epithelial cells, it can be under- 
stood why severe and persistent vascular reactions 
were often elicited by protracted episodes of low- 
intensity hyperthermia that failed to harm the epi- 
dermis (see Figure 13). 

There was considerably greater individual vari- 
ation among human subjects than there was among 
pigs in respect to the vascular reactions to cutaneous 
hyperthermia. The variability of dermal vascular re- 
actions in human subjects was so great and the num- 
ber of reactions studied in this investigation was so 
few that little could be inferred as to the extent to 
which the animal data apply to human skin. The im- 
pression was gained that the thermal stimulus neces- 
sary to cause visible erythema in most human sub- 
jects was substantially lower than that required to 
elicit erythema in pigs. In man the change in skin 
color was usually more intense and of longer duration 
than that in the pig after an identical exposure. 

That an active circulation of blood was maintained 
through the dilated capillaries of an evanescently 
erythematous skin was indicated in part by the pink 
or red color of the surface and in part by the fact that 
the surface temperature during such a reaction was 
characteristically between 0.5 and 1.5 degrees higher 
than that of the adjacent skin. 


An evanescent erythematous reaction to heat could 
not as a rule be recognized in sections prepared for 
microscopic examination. Vessels, the seat of physi- 
ological dilatation, usually contracted during or im- 
mediately after excision, and it was difficult or im- 
possible to distinguish a sample of physiologically 
hyperemic skin from one that was normal or 
ischemic. 

If cutaneous hyperthermia was prolonged to be- 
tween 40 and 60 per cent of the minimum time re- 
quired for the production of transepidermal necrosis 
in either man or pig, it characteristically resulted in a 
more severe and pathological vascular disturbance 
which led to edema and cyanosis and which persisted 
for days rather than minutes or hours. That the flow 
of blood through the dilated capillaries was slowed 
was indicated by the blue or purple color of the sur- 
face in contrast to the pink or red color caused by the 
more evanescent active hyperemia. The surface tem- 
perature of such a lesion during the first few hours 
was frequently found to be from 0.5 to 2 degrees be- 
low that of the adjacent normal skin. That the re- 
action was pathological rather than physiological was 
also indicated by the fact that in both man and pig it 
was almost invariably accompanied by cutaneous 
edema. Within the first hour after the onset of a 
vascular injury of this grade, the water content of 
the dermis was observed to increase by as much as 
100 per cent. 

Microscopic examination of reactions of this type 
at varying periods after exposure in the pig confirmed 
the clinical observation that heat may cause a severe 
disturbance of the dermal blood vessels in both pig 
and man without causing recognizable damage to the 
epidermis. The capillaiy loops of the dermal papillae 
became dilated and elongated and filled with closely 
packed masses of erythrocytes. Separation of collagen 
fibers by edema fluid was obvious and perivascular 
mantles of extravasated erythrocytes were often 
seen. The escape and extravascular deterioration of 
erythrocytes in such a lesion was often sufficient to 
result in brown discoloration of the target area for as 
long as a week. Extravascular fibrin was not encoun- 
tered nor did collagen fibrils appear to be swollen. 
Between 12 and 24 hours after such an injury was 
sustained, occasional polymorphonuclear leucocytes 
were found in the edema fluid. Neither thrombosis 
nor visible alteration in the vascular endothelium 
was seen, despite the fact that superficial vessels 
were filled by static, sausagelike agglomerates of red 
blood cells. 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


Reversible Impairment of Epidermal Anchorage 

During most, and possibly all, injurious episodes of 
cutaneous hyperthermia in which the temperature of 
the dermis was maintained for a sufficient time at 
49 C or higher, there was a brief interval subjacent to 
the threshold for transepidermal necrosis in which 
the adhesion of epidermis to dermis was impaired. 

The attainment of this degree of injury was recog- 
nized by the ease with which the epidermis could be 
dislodged by friction. If the exposure was discontin- 
ued before further injury was sustained and if the 
loosened epidermis was not dislodged either by 
trauma or vesication, the change was often reversible 
in the case of the pig and after 12 or 18 hours the 
original firm anchorage of the epidermis was usually 
regained. Unless the exposure had been excessive, 
such injuries subsided without further evidence of 
cell death. 

If skin altered in this manner was protected against 
mechanical artifact, there was no microscopic evi- 
dence either in the basal epithelial cells or in the un- 
derlying dermis by which impairment of the epi- 
dermal anchorage could be recognized. If, however, 
sufficient friction was applied to the temporarily in- 
secure porcine epidermis to cause its detachment, 
microscopic examination revealed a fringe of up- 
rooted or fractured tonofibrils protruding from the 
lower ends of the detached basal epithelial cells. The 
protruding fibrils appeared to have been pulled out 
of their anchorage in the superficial dermal felt work 
of collagen fibers. It was not determined whether the 
essential change responsible for such epidermal in- 
stability was a deterioration of the extracellular ex- 
tensions of the tonofibrils which predisposed them to 
rupture or a softening of the dermal collagen in which 
they were embedded. The latter was considered the 
more plausible explanation of the phenomenon. In 
man it is doubtful that the tonofibrils of the epi- 
dermal cells have much if anything to do with the 
attachment of epidermis to dermis. In human skin, 
the epidermis appeared to be cemented to, rather 
than rooted in, the dermal collagen. 

It has already been indicated that when porcine 
skin sustained this type of cutaneous burn, recovery 
sometimes took place within 24 hours without death 
of cells, providing the damaged area was protected 
against mechanical disturbance during that period 
when its anchorage to the dermis was insecure. 

Too few appropriate specimens of human burns 
were available for microscopic examination to permit 
conclusions regarding the threshold at or the fre- 


quency with which this particular type of first-degree 
thermal injury occurs in man. The opinion was gained 
from clinical observations of human burns that ther- 
mal exposures insufficient to cause primary epider- 
mal necrosis may result in a temporary impairment 
in the adhesion between epidermis and dermis. If 
such a temporarily insecure layer of epidermis is de- 
tached by friction or vesication, the detached cells 
Avould undoubtedly die. Thus, it is entirely possible 
that the phenomenon of vesication results, in some 
instances, in secondary destruction of human epi- 
thelial cells that would otherwise survive. If this be 
true, and if the thermal exposure has been insuffi- 
cient to cause primary transepidermal necrosis, the 
immediate institution of pressure to prevent epi- 
dermal displacement by vesication should predispose 
to early and uncomplicated healing of what might 
otherwise become an open lesion. 

Irreversible Thermal Injury of EIpidermal 
Cells 

Material for microscopic study was available from 
almost every conceivable kind, grade, and stage of 
thermal injury of the skin of the pig. Although a wide 
range of experimental thermal injuries of human 
skin was studied clinically, most of the burns that 
were available for microscopic examination were ob- 
tained from autopsies. Thus, there was no direct in- 
formation regarding the intensity or duration of the 
thermal exposures that were responsible for most of 
the burns of human skin that were studied micro- 
scopically. The impression was gained, however, 
that, apart from the phenomenon of vesication, the 
cytological changes induced by heat in the epidermis 
of man were similar, if not identical, to those ob- 
served in the pig (see Figures 17 to 22). Attention 
has already been directed to the fact that the time- 
temperature threshold for the destruction of epi- 
dermis is almost identical in human and porcine skin 
(see Figure 14). 

The first manifestation of irreversible thermal in- 
jury of the epidermis was a change in the distribu- 
tion of water and solids within the nuclei of the cells 
of the intermediate zone. As the nuclei swelled, their 
chromatin granules coalesced to form compact cres- 
centric masses immediately beneath and attached to 
one side of the nuclear membranes (Figure 20) . When 
the swollen nucleus ruptured, the peripherally dis- 
tributed chromatin contracted to form a dense and 
irregularly shaped central mass which remained sep- 
arated from the surrounding cytoplasm by clear fluid. 


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Figure 17 Figure 18 

Photographs of severe first-degree burns of porcine (Figure 17) and human (Figure 18) skin showing degenerative 
changes in epidermis. In Figure 17, there is generalized pyknosis of nuclei and it is not likely that any epidermal cells 
included in picture would have recovered. In Figure 18, changes are focal rather than general and most of altered nuclei 
are swollen and show peripheral displacement of chromatin. This type of nuclear change precedes that shown in Figure 17. 
Both specimens were excised within an hour after injury was sustained. In both instances, epidermal attachment to 
dermis was insecure and lesion shown in Figure 18 would probably have gone on to vesication in normal course of events. 
Magnification 400 X. 



Figure 19 Figure 20 

Photographs of early second-degree burns of porcine (Figure 19) and human (Figure 20) skin showing early spontaneous 
detachment of epidermis from dermis. Vacuolar cytoplasmic disintegration of basal cell layer has been added to nuclear 
changes similar to those shown in Figures 17 and 18. In Figure 19, tonofibrils that were uprooted from their anchorage 
in dermis can be seen projecting from detached basal cells. Magnification 400 X. 


This fluid, whether extruded into the nuclear lacuna 
or contained within the distended nuclear membrane, 
was faintly basophilic and sometimes contained a few 
fine Feulgen-positive fragments of chromatin. 

Pyknosis of nuclei was by no means pathogno- 
monic of thermal injury. Spontaneous nuclear pykno- 
sis was sometimes seen in the upper zone of normal 
unheated epidermis and was caused by injuries other 
than heat. 

In the case of subthreshold exposures sufficient to 
injure the upper layers of epidermal cells but insuffi- 
cient to cause transepidermal necrosis, the types of 


nuclear change which have been described were fre- 
quently focal and difficult to distinguish from quali- 
tatively similar changes in control material. Even 
though it could be plausibly assumed that all of the 
cells at a given level were exposed to the same degree 
of hyperthermia, it was not uncommon to find groups 
of cells with normal appearing nucleuses interspersed 
among those that showed advanced degenerative 
change (Figure 18). The reason for this apparent dif- 
ference in the susceptibility of cells in the same layer 
to heat was not apparent. 

If the thermal exposure was of sufficient intensity 


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STUDIES OF THERMAL INJURY — CUTANEOUS AND SYSTEMIC 




Figure 21 Figure 22 

Photograph of pseudo-vesicle of porcine skin (Figure 21) and early true vesicle of human skin (Figure 22). In each, trans- 
epidermal necrosis appears to be complete. In porcine skin, detached epidermis would have remained in situ as flaccid 
membrane. In human skin, detached epidermis would have been elevated by collection of edema fluid between it and 
dermis. Magnification 400 X . 


or duration to cause irreversible cellular injury, 
nuclear changes of the kinds described in the fore- 
going paragraphs were usually apparent immediately 
after the conclusion of the episode of hyperthermia. 
This was not invariably the case, however, and after 
certain exposures at relatively low temperature (un- 
der 47 C) a postexposure interval of between 6 and 
12 hours was sometimes required for the develop- 
ment of recognizable nuclear alterations. Moreover, 
if the exposure was of sufficient severity to cause 
pseudovesication in the pig or true vesication in man, 
many of the nuclei which were apparently undam- 
aged at the conclusion of the exposure disintegrated 
during the next 24 hours. 

If the episode of hyperthermia was such as to 
cause visible alterations in nuclear structure, there 
was inhibition of mitotic division throughout the en- 
tire area of exposure for many hours. No evidence 
was derived from the microscopic study of subthresh- 
old exposures to indicate that hyperthermia predis- 
posed to acceleration of mitotic activity. The impres- 
sion was gained that nuclear swelling with coales- 
cence of chromatin granules constituted evidence of 
an irreversible cellular change and invariably led to 
premature death and desquamation of the altered 
cells. 

In the pig, the irreversibly damaged epidermal cells 
were gradually desquamated over a period of a week 
or 10 days in the form of thin brown scales. 

Alterations in the appearance of nuclei in the upper 
and intermediate layers of epithelium were thought 
to provide the earliest morphological evidence of 
primary thermal injury of the epidermis and were 


frequently encountered without perceptible damage 
to the cells of the basal layer. Characteristically, the 
earliest change in the basal cell layer caused by hy- 
perthermia was cytoplasmic rather than nuclear. 
The injured basal cells swelled and their cytoplasm 
became vacuolated and increasingly acidophilic 
(Figures 19 and 20). The vacuolization appeared to 
be due in part to imbibition of fluid and in part to 
redistribution of water and solids within the cells. 

The fluid contained within the cytoplasmic vacu- 
oles was clear, nonsudanophilic, and sometimes con- 
tained a delicate mesh of granular amphophilic debris. 
With severe injury there was widespread rupture 
and disintegration of the lower ends of the basal cells. 

17.7.4 Second-Degree Reactions 
Transepidermal Necrosis 

The time-temperature characteristics of exposures 
just sufficient to cause transepidermal necrosis in 
both man and pig are indicated in Figure 14. In man, 
whether or not a thermal exposure has destroyed the 
epidermis can usually be determined by the occur- 
rence or nonoccurrence of vesication within the first 
24 hours. To recognize with certainty during the first 
day or two after a near-threshold exposure whether 
or not porcine epidermis has been destroyed, the skin 
must be excised and examined microscopically. When 
the area of injury was 7 mm in diameter and when 
the duration and intensity of the exposure was at or 
not far above the threshold required for transepi- 
dermal necrosis, the time usually required for com- 
plete healing was between 5 and 10 days in the pig 
and between 1 and 2 weeks in man. 


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In the pig, microscopic evidence that an exposure 
had been sufficient to cause transepidermal necrosis 
was provided by the changes that had occurred at 
the basal cell level. With the disintegration of the 
cytoplasm of the proximal or lower ends of the in- 
jured basal cells, there was at first focal and later 
extensive spontaneous detachment of the epidermis 
from the dermis. In the pig, the amount of fluid that 
collected beneath the loosened epidermis was never 
sufficient to produce true vesication. 

With still more severe hyperthermia, the cyto- 
plasmic disintegration of the basal cells was followed 
by nuclear changes similar to those seen in the more 
superficially located cells. If the epidermal detach- 
ment was incomplete, stretching and attenuation of 
the remaining bridging cells and their nuclei was 
often seen. Such attenuated masses of chromatin were 
often stretched to two to three times the original 
length of the entire cell. 

In the event that the surface temperature of the 
epidermis was brought rapidly to a level of 55 C or 
higher and maintained at that level for a period 
longer than that necessary to cause cell death, trans- 
epidermal coagulation was likely to occur so quickly 
as to inhibit recognizable redistribution of intra- and 
extracellular fluids. In such an event, neither the 
cytoplasm nor the nucleuses of the epithelial cells 
appeared swollen (Figure 25). On microscopic ex- 
amination, both appeared shrunken, the former being 
intensely and uniformly acidophilic and the latter 
small and homogeneously basophilic. 

Vesication 

Attention has already been called to the fact that 
a common effect of heat on the skin of both man and 
pig is impairment of the attachment of the epidermis 
(Figures 21 and 22) to the dermis, and the opinion 
expressed that this may be due either to a change in 
the physical state of the superficial dermal collagen 
or to disruption of the basal layer of epithelial cells. 
A common collateral effect of cutaneous hyperther- 
mia, and one that is essential to true vesication, is an 
outpouring of fluid from the dermal capillaries. 

When a thermal exposure of human skin was suffi- 
cient to impair the attachment of the epidermis, the 
amount of edema fluid that collected between it and 
the dermis was usually sufficient to elevate and 
stretch the entire layer of dead, dying, and living 
cells and to form a vesicle. Although vesication of 
human skin was usually an almost immediate re- 
sponse to a thermal exposure of sufficient severity to 


cause primary epidermal injury, there were several 
circumstances in which it was either delayed or in- 
hibited. 

Delayed vesication was most frequently seen after 
long-time exposures at low temperatures or after 
flash exposures at high temperatures. In both cir- 
cumstances it seemed likely that the delay was due 
to the fact that the vascular damage was relatively 
mild, and that hours rather than minutes were re- 
quired for enough fluid to collect beneath the dam- 
aged epidermis to form a vesicle. 

Another circumstance in which vesication was de- 
layed or prevented was when the injury was so over- 
whelming that the dermis and its superficial capil- 
laries were almost immediately coagulated. With 
such thermal injury, the level at which edema de- 
veloped was too deep to result in vesication. 

Thus, in man, the nonoccurrence of vesication 
after a thermal exposure sufficient to cause severe 
injury of the epidermis may mean that the dermal 
hyperthermia was either inadequate to result in 
edema or that it was so overwhelming that the super- 
ficial capillaries were almost immediately occluded. 

In no instance was true vesication of porcine skin 
observed. This was true despite the fact that many of 
the injuries met at least two prerequisites to vesicle 
formation: namely, sufficient vascular injury to re- 
sult in dermal edema and sufficient impairment of 
the adhesion between epidermis and dermis to per- 
mit easy mechanical detachment of the former (Fig- 
ure 21). Failure of the pig to vesicate appeared to be 
due to the fact that the amount of edema fluid that 
penetrated the surface of the dermis was never suffi- 
cient to elevate the epidermis. In the absence of evi- 
dence to the contrary, a tenable explanation for 
nonvesication in the pig is that an episode of hyper- 
thermia that is sufficient to impair the attachment 
of the epidermis to the dermis characteristically al- 
ters either the superficial felt work of dermal collagen 
fibers or the walls of the capillaries contained by it 
in such a way that they become virtually imperme- 
able to edema fluid. 

The nature or, for that matter, the existence of 
this theoretical alteration in the permeability of the 
collagen or the capillary walls was not disclosed by 
microscopic examination. When the severity of an 
exposure was considerably in excess of that required 
to destroy the epidermis, swelling of the superficial 
dermal collagen and occlusion of its capillaries could 
be recognized. There was, however, a wide range of 
exposures between the threshold for epidermal ne- 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 




Figube 23 Figure 24 

Photographs of mild (Figure 23) and moderately severe (Figure 24) third-degree thermal reactions in porcine .epidermis 
24 hours after injury. Both injuries were produced by episodes of hyperthermia that were of low intensity (under 55 C) 
and long duration. In both instances, irreversibly injured dermal tissue will undergo autolysis and organization. 
Magnification 400 X. 


crosis and that for recognizable swelling of collagen 
or occlusion of capillaries in which the microscopic 
examination of the pig’s skin disclosed no explana- 
tion for the failure of porcine skin to vesicate. 

17.7.5 Third-Degree Reactions 
The more a thermal exposure exceeded the thresh- 
old required for destruction of the epidermis, either 
in respect to temperature or time, the deeper the in- 
jury and the longer the recovery period necessary for 
repair and regeneration. In both pig and man, several 
weeks represented the minimum healing time if a 
significant degree of dermal injury had been sus- 
tained. 

Further Changes in Epidermis 

In the case of the pig, prolonged exposure at a rela- 
tively low surface temperature (under 55 C) caused 
relatively little additional change in the microscopic 
appearance of the epidermis. In the higher range of 
surface temperatures, significant prolongation of the 


rate of duration of exposure beyond the time neces- 
sary to destroy the epidermis modified the quality of 
the superficial changes both in human and porcine 
skin. In man, vesication was permanently inhibited 
and in both man and pig the loosened epidermis be- 
came reattached to the damaged dermis. Early solidi- 
fication and contraction, both cytoplasmic and nu- 
clear, occurred before there was opportunity for the 
development of the retrogressive changes observed 
in first- and second-degree reactions. The higher the 
temperature, the shorter the time required to cause 
transepidermal coagulation. With exposures to super- 
heated air, desiccation was superimposed on the 
effects of heat, and, soon after the temperature rose 
above 300 C, carbonization of the dry tissue began 
to take place. 

Red and Pale Burns 

The surface color of third-degree burns ranged 
from pale gray through red, purple, and brown to 


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Figure 25. Third-degree thermal reaction in porcine 
skin showing coagulation of epidermis and dermis 24 
hours after injury. Bundles of denatured dermal colla- 
gen appear swollen and homogeneous and become in- 
creasingly basophilic. Thermal reactions of this type 
were encountered only where surface temperature had 
been brought to and maintained at level of 55 C or 
higher. Magnification 400 X. 

black, depending on certain attributes of the ex- 
posures responsible for their production. 

A black or carbonized surface resulted from ex- 
posures at temperatures in excess of 200 C (Fig- 
ure 28). The precise temperature at which carboniza- 
tion began was not determined. 

A red, purple, or brown surface, due to the presence 
of blood in the superficial layer of the skin, resulted 
from exposures in which the dermal temperature was 
raised slowly enough to permit advanced engorge- 
ment of the superficial capillary plexus before the 
occurrence of coagulation. 

A gray or ischemic surface indicated that the upper 
portion of the dermis had undergone thermal coagu- 
lation before the superficial capillaries had become 
fully engorged. 

The reciprocal relationships of time and tempera- 
ture as they relate to the visibility of hemoglobin 
beneath the surface of a third-degree thermal re- 
action is shown in Table 10. It was found that at at- 
mospheric pressure and at surface temperatures of 
65 C or lower burns appeared superficially hyperemic 
regardless of the duration of exposure. When a 70 C 
surface exposure was interrupted at the end of 2 sec- 
onds, the lesion remained red, but, if it were pro- 



Figure 26. Photograph of third-degree thermal reac- 
tion in porcine skin 72 hours after injury. Exudative 
cells have migrated into interstices between bundles of 
coagulated collagen. Precise level at which this injury 
will be stablized is not yet apparent. Healing will be 
slow because of resistance of denatured collagen to 
autolysis and organization. Magnification 400 X . 

longed to 3 minutes, the zone of reactive hyperemia 
became overlaid by so thick a layer of coagulated 
tissue that it was no longer visible. Above 70 C all 
exposures of a second or longer coagulated the super- 
ficial plexus of dermal capillaries so rapidly that most 
or all of the blood contained in them was displaced to 
a level too deep to be seen from the surface. 

Pooling of Blood in Hyperemic Burns 

A qualitative impression of the pooling of blood in 
the dilated cutaneous vessels after an injurious epi- 
sode of hyperthermia was derived from the photo- 
micrographs shown in Figure 11. In order to learn 
something of the actual amount of blood that was 
present in such lesions, samples of both normal and 
hyperemic skin were excised for chemical examina- 
tion. Samples of skin and subcutaneous tissue having 
an area of 25 cm ^ and extending to the deep fascia 
were taken from the lateral thoracic area of each of 
nine pigs and their iron content was determined. 
Two of the samples represented normal skin and 
the other three were from areas of hyperemic burn- 
ing. 

It is apparent from the results of the experiments 
shown in Table 16 that a relatively large proportion 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 



Figure 27. Transcutaneous coagulation resulting in 
deep ischemic burn. Five-minute exposure to air at 
200 C. Surface temperature of skin not known but 
probably in excess of 55 C. Epidermis has become re- 
attached to dermis. Magnification 85 X . 

of the total circulating blood of an animal may be 
pooled in the skin and subcutaneous tissue as a re- 
sult of thermal injur^^ Calculations based on the 
amount of recoverable iron per unit of surface area 


Table 16. Pooling of blood in the subcutaneous vessels 
due to thermal injury. 


Condition of 
skin 

Mg iron in 

25 cm^ sample 

Est. cc of blood 
in 25 cm^ sample 

Normal 

0.06 

0.11 


0.10 

0.18 

Moderate 

0.14 

0.25 

hyperemia 

0.29 

0.51 

Severe 

0.56 

1.00 

hyperemia 

0.60 

1.10 


0.40 

0.70 


0.39 

0.70 


0.37 

0.67 


of burned skin in relation to the body weight indi- 
cated that as much as 30 per cent of the erythrocytes 
of an animal suffering from generalized cutaneous 
hyperemia could be accounted for in the skin and 
subcutaneous fat. 

Effect of Compressive Hyperthermia on Color 
OF A Burn 

In a preceding section attention was called to the 
fact that compression of the skin surface during ex- 



Figure 28. Carbonization of surface and intense baso- 
philia of coagulated dermis due to 2.5-minute exposui-e 
of skin at 405 C. Effects of ambient heat augmented by 
radiant energy. Magnification 85 X. 

posure to heat did not increase the vulnerability of 
the epidermis to thermal injury. It was found, how- 
ever, that compression of the skin was capable of 
modifying the superficial color of the burn even 
though there was no quantitative increase in its 
severity. To determine the circumstances in which 
compression of the skin during an episode of hyper- 
thermia may modify subsequent surface color of the 
lesion, the experiments summarized in Table 1 7 were 
undertaken. In some, hot water was applied at at- 
mospheric pressure; in others, it was applied with a 
compressive force of 120 mm of mercury. 

The results of these exposures indicated that the 
color of burns resulting from surface temperatures 
lower than 55 C was not affected by pressure, but 
that an increase in pressure during exposures at sur- 
face temperatures of 60 C or higher determined 
whether the surface of the resulting burn would be 
ischemic or hyperemic. Thus, an exposure at at- 
mospheric pressure at GO C produced a red burn even 
though it was extended for as long as 5 minutes. 
With increase in pressure, a 2-minute exposure at the 
same temperature resulted in a pale burn and yet the 


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349 


Table 17. Experiments to determine the circumstances 
in which compression of the skin during an episode of 
hyperthermia may modify subsequent surface color of 
the lesion. 


Temp 

of 

surface 

(C) 

Duration of 
hyperthermia 
(seconds) 

Pressure 

on 

skin 

(mm Hg) 

External appearance 
of burn 24 hours 
after exposure 
Ischemic Hyperemic 

70 

5 

0 


4- 


5 

120 

+ 


65 

30 

0 


+ 


30 

120 


+ 


60 

120 

+ 



1,200 

0 


+ 

60 

60 

0 


+ 


60 

120 


4 - 


120 

120 

+ 



300 

0 


+ 

55 

1,800 

0 


+ 


1,800 

120 


+ 


depth to which the tissue had been destroyed in the 
latter was less than that to which it had been de- 
stroyed in the former. 

At 70 C a 5-second exposure at atmospheric pres- 
sure resulted in a red burn, but, with an additional 
pressure of 120 mm of mercury, the resulting burn 
appeared ischemic. 

Microscopic examination of these lesions provided 
evidence that the color of a burn was not a reliable 
criterion by which to judge its depth. After hyper- 
thermic episodes of comparable duration and at the 
same surface pressure, a red surface color usually 
indicated that the lesion was less severe than one 
having a gray surface. Without knowledge of time, 
temperature, or surface pressure during the period of 
exposure, it is not possible to estimate the relative 
severity of burns on a basis of surface color. 

Other Effects of Heat on Dermis 

After edema and pericapillary extravasation of 
erythrocytes the earliest recognizable extravascular 
alteration of the dermis was swelling of the collagen 
fibers. This occurred first in its most superficial layer 
w^here, in the case of porcine skin, the projecting 
tonofibrils of the basal epithelial cells were imbedded 
in the collagen of the subjacent connective tissue. 

As the intensity and duration of the hyperthermia 
increased, the corium tended to lose its fibrillar char- 
acter and was converted into a thin lamella of homo- 
geneous acidophilic material as though its individual 
fibers had been converted to a gel. With increasing 
exposure the swelling of collagen became apparent at 
greater and greater depths in the underlying con- 
nective tissue (Figure 25). Expansion of collagen 


bundles tended to collapse the dermal blood vessels 
and the loose areolar tissue that surrounded them. 
Visible edema receded in advance of this type of al- 
teration as though the fluid were imbibed or dis- 
placed by the denatured collagen. Not until 24 or 
48 hours had elapsed was it possible by microscopic 
examination to recognize the line of demarcation be- 
tw^een reversible and irreversible dermal injury (Fig- 
ures 23 and 24). 

From the intact blood vessels of the deeper and 
relatively uninjured tissues, leucocytes migrated up- 
Avard through the perivascular interstices and into 
the zone of denatured collagen. A frontier was even- 
tually established betw^een the tissue capable of re- 
generation and repair and that destined to be seques- 
tered in the form of a desiccated crust. The deeper 
the lesion, the longer the time required for the stabi- 
lization of such a frontier. The transition betw^een the 
obviously necrotic tissue of the upper dermis and the 
least disturbed tissue of the deepest portion of the 
zone of hyperthermia was a gradual one. Exudation 
of leucocytes occurred wdthin a few hours and within 
24 hours usually served to delineate the zone within 
w^hich the plane of irreversible injury would eventu- 
ally become stabilized. Within 2 or 3 days fibroblasts 
and new capillaries began to push up toward the sur- 
face in the interfascicular interstices of the denatured 
collagen. The least affected connective tissue at the 
base of the reaction zone recovered quickly and with- 
out apparent loss of fixed tissue cells. The fate of the 
more severely injured collagen varied according to 
the extent to which it had been denatured. Thermal 
denaturation of collagen at temperature levels under 
55 C did not usually result in the kind of coagulative 
change that made the collagen resistant to subse- 
quent autolysis and organization (Figure 26). Col- 
lagenous denaturation at temperatures over 55 C 
often resulted in an irreversible type of coagulation 
w^hich resisted lysis and eventually led to sequestra- 
tion en masse. Thus, deep and severe burns resulting 
from surface exposures lower than 55 C were likely 
to remain soft and red and the necrotic tissue was 
susceptible to organization. Deep burns resulting 
from higher temperatures w^ere characteristically 
firm and pale and the necrotic tissue w^as seques- 
tered rather than organized. After exposures to 
temperatures between these two extremes the dead 
and damaged connective tissue was infiltrated by 
leucocytes and penetrated by granulation tissue and 
its necrotic elements w^ere gradually resorbed and 
replaced by new connective tissue. 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


During the time required to establish the level of 
irreversible injury, tentative tonguelike masses of 
new epithelial cells grew out from the margins of the 
lesion and from the viable roots of partially destroyed 
hair follicles as though they were seeking a suffi- 
ciently well-stabilized layer of connective tissue to 
provide support and nutrition. Repeated crops of 
such new epithelial cells extended over or into the 
granulation tissue and failed to survive, for reasons 
not disclosed by microscopic examination. 

The number of experimentally produced deep 
burns of human skin was not great enough to draw 
any definitive conclusion regarding the relative rates 
of healing of such lesions in man and pig. The impres- 
sion was gained, however, that lesions of similar area 
and depth heal more rapidly in the pig. 

17.7.6 Summary 

Comparison of effects of heat on human and por- 
cine skin : In a previous section of this chapter it was 
sho\\Ti that the quantitative relationships between 
temperature, duration of hyperthermia, and depth 
of injury were similar in human and porcine skin. 
In this section it has been shown that there is a strik- 
ing qualitative similarity between the microscopic 
alterations that are caused in human and porcine 
skin by hyperthermia. The most important quali- 
tative difference is that true vesication was not ob- 
served in the pig, whereas in man it is a character- 
istic cutaneous reaction to certain types of thermal 
injury. The reason for this difference has been dis- 
cussed. Attention was called to the fact that vesica- 
tion is an undesirable phenomenon in that it may re- 
sult in the separation and death of viable epidermal 
cells and that there is reason to believe that healing 
of certain burns in man would be hastened if vesica- 
tion could be prevented. 

Sequence of changes caused by harmful episodes of 
hyperthermia : The earliest changes are latent, in the 
sense that they are not associated with visible altera- 
tion in the appearance of the damaged cells. Such 
changes are reversible. 

Beyond the stage of latent injury, the pathological 
changes produced by exposure to heat are of two 
kinds: those that represent the reaction of living 
tissue to injury and those that represent the effects 
of excessive heat on cells and intercellular substances 
that have already sustained irreversible injury. The 
former may or may not be reversible and differ in 
nature according to the type of cell or tissue in which 
the reaction has occurred. The latter are of impor- 


tance principally with respect to the extent to which 
such postvital thermal denaturation interferes with 
the organization and disposal of the necrotic tissue. 
Both types of reactions have been described in detail. 

17.8 CONSIDERATION OF THE NATURE 
OF PHYSICAL AND CHEMICAL CHANGES 
INDUCED IN TISSUE BY 
HYPERTHERMIA ' 

17.8.1 Introduction 

Ideally, an attempt to elucidate the precise nature 
of the changes produced by heat on the skin should 
be based on a knowledge of the various physical and 
chemical phenomena that are normally essential to 
the survival and functional integrity of the living 
cells that comprise cutaneous tissue. If it were then 
possible to observe the alterations of each of these 
physical and chemical functions with temperature, a 
direct solution of the problem of how heat injures the 
skin might be reached. Unfortunately, detailed in- 
formation regarding the basic physical and chemical 
properties of the skin or the effects of temperature 
thereon does not exist. In fact, very little qualitative 
and almost no quantitative data are available on 
even the general physical and chemical attributes of 
skin constituents as of to date. It is apparent, then, 
that any consideration of temperature-induced physi- 
cal and chemical changes which may lead to thermal 
death must be based on the known in vitro effects of 
temperature on substances that are akin in function 
and/or properties to those which probably occur in 
cutaneous tissues. 

Since nearly all the quantitative experimental data 
derived from this investigation deal with epidermis, 
the ensuing discussion will be limited primarily to 
this tissue. In Sections 17.6.5 and 17.9.3, these data 
are shown to be quantitatively predictable by the 
standard form of a rate equation,^® specifically, equa- 
tion (7). In this equation there appear two empirical 
and experimentally determinable constants, namely, 
A and AE ; any theoretical consideration of the cause 
of thermally induced transepidermal necrosis should 
take into account, at least qualitatively, the numeri- 
cal values of these quantities. Aside from certain 
general conclusions regarding the entropy of the 
overall process,^® little specific information can be 
obtained from the numerical value of A, since this 
constant is intimately connected with the as yet un- 

^ By F. C. Henriques, Jr. 


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351 


known detailed physical and chemical properties and 
functions of the epidermal constituents. This is not 
the case, however, with A£', and thus, before proceed- 
ing further, a brief general consideration of the na- 
ture of the activation energy in calories per mole, 
is in order. 

17.8.2 Thermal Injury and Energy of 
Activation 20 

In general, the kinetics of any given physical 
and/or chemical process depends upon the total 
energy content of the constituents involved. If this 
energy content is less than a certain critical value, 
known as the activation energy, the process cannot 
take place; if the energy content is equal to or greater 
than this critical value, the process may take place. 
Thus the rate of the process will be proportional to 
the fraction of these constituents which, collectively 
considered, possess an energy content at least equal 
to the activation energy. This fraction is deduced 
from the Maxwell-Boltzmann energy distribution 
law, which states that 

j- ^ ^-AE/R{T + 273) 

where f is this fraction, and the remaining symbols 
have been previously defined. Equation (16) deter- 
mines only the temperature coefficient of a rate 
process, since, as shown by equation (7), the rate of 
a process is also proportional to one other factor that 
is essentially nondependent on temperature, namely 
A. 

Thus, the rate of any conceivable process that may 
result in cell death, whatever it may be, depends 
upon a critical energy content of the participants. 
The fraction of the participants, collectively consid- 
ered, having this energy is determined by the activa- 
tion energy and the temperature [equation (16)]. 
The availability of this fraction is requisite but not 
in itself sufficient to allow the process to proceed. 

An inspection of equation (16) shows that the 
temperature coefficient of any kinetic process is a 
strong function of the activation energy; for example, 
in the neighborhood of 50 C, the rate of a process 
with an activation of 1, 10, or 100 kcal/mole will be 
altered by about 0.4 per cent, 7 per cent, or 70 per 
cent, respectively, per unit change in temperature 
in C. 

The kinetics of a considerable number of physical 
and chemical phenomena have been studied in detail 
and it is possible to classify all rate processes and, 
hence, in particular, those mechanisms which may be 


of considerable importance in the general considera- 
tion of thermal injury, according to the order of 
magnitude of their activation energy. 

During the past 50 years, numerous theories ® have 
been proposed to explain thermally induced injuries 
in living organisms. Before applying the above cri- 
teria to the mechanisms involved in these theories, 
it is necessary briefly to characterize the attributes 
of a living cell.^^ 

The living cell appears to consist of a semirigid 
relatively nonsoluble framework (e.g., nucleus, nu- 
clear wall, and cell wall) that is primarily protein in 
nature. This aggregate is bathed in an aqueous intra- 
cellular fluid which contains both particulate (e.g., 
micellar) and soluble constituents ranging from 
simple ions to proteins of extraordinary complexity. 
Aside from certain purely physical attributes (e.g., 
permeability, contractibility, elasticity, cohesiveness, 
rigidity, and tensile strength), this protoplasmic 
entity respires, excretes, synthesizes all imaginable 
types of molecules, utilizes and liberates energy, and 
reproduces in a manner that perpetuates its own 
kind. This exceedingly complex metabolic activity is 
apparently both catalyzed and precisely controlled 
by a multiplicity of enzymatic proteins and function- 
ally allied molecules which contribute to both the 
structural framework and the cytoplasmic fluid. 

In view of this complex picture, no theory of ther- 
mal injury can be considered tenable unless it takes 
into account these completely integrated and pre- 
cisely balanced phenomena, which, taken as a whole, 
comprise cell life. Unfortunately our knowledge of 
these phenomena is as yet meager and is limited to 
isolated observations on living protoplasm (e.g., cell 
respiration, mitosis, diffusion of a few substances 
through cell walls) and to certain chemical and physi- 
cal properties and functions of a few of the molecules 
that can be extracted in a presumably unaltered 
state from dead cell brei. 

Nevertheless, even on the basis of this limited in- 
formation, it is interesting to speculate with regard 
to the general kinds of mechanisms that may be of 
importance in explaining the quantitative time- 
temperature relationship that results in irreversible 
epidermal injury as judged morphologically. These 
injury data (Sections 17.6.5 and 17.9.3) showed that 
episodes of transepidermal injury are quantitatively 
predictable by a rate equation with an activation 
energy of 150 kcal/mole over the entire experi- 
mental skin temperature range (44 to 70 C). 

The theories ® that have been advanced to explain 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


thermal injury may be classified into three general 
groups. 

1. Thermal alterations in proteins. In view of the 
many varied functions of proteins in the maintenance 
of normal cell life, it is obvious that even minor ther- 
mally induced alterations of these molecules may 
result in profound irreversible injuries. Thus, for 
example, these thermal protein changes could pro- 
duce an increased permeability of the nuclear and/or 
cell wall, structural alterations in the nucleus itself, 
disintegration of the protein mitochondria present 
in the cytoplasm, inactivation of enzymes. 

Many quantitative studies have been made 
of the effects of temperature on proteins, and altera- 
tions that proceed at a measurable rate between 0 to 
100 C with activation energies in excess of 50 kcal/ 
mole are not unusual. The heat inactivation of in- 
vertase {^E = 110 kcal at pH 4 and = 52 kcal 
at pH 5.7) and of peroxidase (A£' =189 kcal), and 
the heat denaturation of egg albumin (AE' =132 kcal 
at pH 5) and of hemoglobin (AE' = 76 kcal at pH 6.8) 
are a few of the many examples. 

Thus, the morphological observations of protein 
dissolution and/or coagulation on which the quanti- 
tative judgment of transepidermal necrosis is based 
may well be directly due to the thermal alterations 
of as yet unknown proteins present in epidermal cells. 

2. Other possible alterations in metabolic processes. 
Since temperature affects, to a greater or lesser de- 
gree, the kinetics and thermodynamics of all chemi- 
cal and physical phenomena, heat may cause altera- 
tions in metabolism irrespective of its effect on pro- 
teins. For example, the entire metabolic equilibrium 
may be upset because of concentration changes in 
some of the individual constituents as a result of 
temperature variations both in rate of diffusion and 
formation and degradation of the chemical reactants 
comprising the process; in fact, because of this ab- 
normal functioning, certain metabolites normally 
present may completely disappear and/or others 
abnormal and toxic in character may arise. There 
can be no doubt that these phenomena do take place 
and that they may cause cell death. 

Many of these metabolic reactions, both en- 
zyme- and nonenzyme-catalyzed, have been studied 
as in vitro processes, and activation energies usually 
between 10 and 20 kcal/mole are found. In certain 
instances the activation energies are less than 10 
kcal/mole but none have been found to exceed 50 
kcal. 

Thus, to date, there is no experimental evidence 


that these types of reactions can lead to a tempera- 
ture coefficient for thermal injury which corresponds 
to that found experimentally for transepidermal 
necrosis. 

3. Nonprotein-induced alterations in the physical 
characteristics of cells. In this group are placed all 
physical phenomena that are characteristic of proto- 
plasm but are not primarily effected by the thermal 
alterations of proteins contained therein. For exam- 
ple, diffusion of metabolites through a cell wall that 
has not undergone chemical alteration is a member 
of this class, whereas changes in diffusion rates that 
are the result of an increased cell wall permeability 
due to the degradation of structural protein are spe- 
cifically excluded, since this phenomenon is classified 
under group (1). 

All of the biophysical rate processes that have been 
studied, such as diffusion through liquids and mem- 
branes, viscosity, rigidity, tensile strength, lique- 
faction, possess activation energies that are usually 
less than 5 kcal/mole, and never in excess of 15 kcal/ 
mole. 

Although these types of mechanisms are undoubt- 
edly potentially capable of causing cell death, they 
are not the instigators of the morphological changes 
that are observed in irreversible epidermal injury. 

Since many fatlike substances are known to melt 
around 45 C, the liquefaction of lipoids has received 
considerable consideration as a potential instigator 
of thermal injury.® From a kinetic viewpoint, the 
rate of melting is a physical process with essentially 
a zero activation energy. This theory would predict 
a sharp temperature threshold for injury, with the 
injury rate becoming nearly a linear function of the 
increment in temperature above threshold value. 
Hence, although liquefaction might account for the 
quantitative epidermal thermal relationships at skin 
surface temperatures between 45 C and 48 C, there 
would be extreme variance with the experimental 
data at the higher skin temperatures. The extent to 
which thermal liquefaction of lipoid substances may 
contribute to cell death in tissues other than the 
epidermis was not investigated. 

In view of the preceding discussion, it can be con- 
cluded that the only biokinetic phenomena known 
to date that can account for epidermal cell death are 
the thermally induced changes in protein structure 
which have an activation energy in the neighborhood 
of 150 kcal/mole. This in no way excludes the in- 
jury propensity of the innumerable mechanisms im- 
plied above, but merely states that all quantitative 


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353 


studies made in this investigation indicate that the 
morphological changes (see Section 17.7.3 and Sec- 
tion 17.7.4) observed in the epidermal tissue can be 
ascribed to these protein alterations. 

As to the number and kinds of proteins involved, 
the specific nature of thermally induced reactions,® 
and the individual rate of each protein alteration, 
nothing can be stated. Further, it is probable that 
at any given hypothermic level any one of these 
numerous protein alterations is potentially capable 
of producing cell death. 


17.8.3 Thermal Injury and Entropy 
and Free Energy of Activation 
With no intention whatsoever of im. plying that the 
thermal effects on living protoplasm can be ascribed 
to the alteration of any single protein, it is of value 
to make for the moment this extreme oversimplifi- 
cation in order to interpret the significance of the 
numerical value of A in the empirical rate equa- 
tion (7) which predicts completely the thresholds of 
transepidermal necrosis. 

In vitro studies on both enzymatic and nonenzy- 
matic proteins have shown that the rate of thermally 
induced changes is first-order and the quantity of 
degraded protein is given by 


P is the amount of protein originally present. Pa is 
the amount of unaltered protein present at the time 
t in seconds. K (1.37 X 10“^® erg/degree), h (6.55 X 
10“^^ erg second), and R (2 cal/degree/mole) are the 
Boltzmann, Planck, and gas constants, respectively. 
T is the temperature in C. AS and AE are the entropy 


« Crozier and his co-workers have used the concept of 
activation energy to interpret many life processes by means of 
some master reaction. This interpretation has been criticized 
by numerous investigators, since it is mathematically 
demonstrable that the constancy or inconstancy of the activa- 
tion energy is neither a necessary nor sufficient condition to 
prove the respective existence or nonexistence of a specific 
master reaction. In Crozier’s investigations, the activation 
energies found were usually in the neighborhood of 10-20 
kcal and, since the great majority of biological reactions are 
in this range, these criticisms are well justified. However, it is 
also mathematically demonstrable that no conceivable com- 
binations of a series of reactions with activation energies 
within a certain bound can produce an overall kinetic process 
with an activation energy out of this bound (e.g., no combina- 
tion of reactions for which 10 kcal > AE < 20 kcal can lead 
to any overall phenomena with an activation energy less than 
10 kcal or greater than 20 kcal). Thus, the interpretation in 
the text is valid. 


and activation energy of the rate process, respec- 
tively. 

Comparing this equation with equation (9) 
where A = 3.1 X 10^® and AE = 150,000 kcal /mole 
remembering that 12 = 1 for the production of trans- 
epidermal necrosis, we find, in the neighborhood of 
50 C, the following numerical relationship for AS in 
cal/degree/mole. 

AS = 398 + 21n ^In ^ (18) 

where Pa/P is that fraction of the original protein 
present which must be thermally altered in order to 
produce epidermal necrosis. 

This equation is extraordinarily insensitive to the 
ratio of P/Pa. Thus, the variation of this ratio from 
100 (99 per cent protein alteration requisite for in- 
jury) to 1.01 (1 per cent alteration required), changes 
AS from 401 to 389. In view of this fact, this analysis 
can be at once generalized to include all of the 
simultaneous inactivations and denaturations of the 
numerous protoplasmic proteins which are thermally 
induced and proceed with an activation energy of 
150 kcal /mole. 

Thus, for the combined effect of these processes, it 
is found that 

AS ^ 395 entropy units. (19) 

The free energy of activation AF can be computed 
from this entropy of activation and the experimental 
activation energy [150 kcal/mole, equation (10)] 
from the following thermodynamic equation. 

AF = AE TAS. (20) 

And in the neighborhood of 50 C (323 A), the fol- 

lowing is obtained : 

AF ~ 22 kcal/mole. (21) 

The occurrence of high energies of activation to- 
gether with large increases in entropy which lead to 
free energies of activation from 20 to 30 kcal in the 
neighborhood of 50 C is a unique characteristic of all 
rates of denaturation of proteins and inactivation of 
enzymes that have been quantitatively studied 

in vitro. 

Certainly, the complete quantitative concordance 
of the numerical constants of an experimental equa- 
tion that predicts epidermal necrosis with the known 
effects of heat on in vitro alterations in protein struc- 
ture is more than coincidence. Considerable confi- 
dence can thus be placed in the statement that ther- 
mally induced injury to living epidermal protoplasm 
is primarily due to changes in some of the nuclear and 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


cytoplasmic proteins which have activation energies 
for thermal degradation in the neighborhood of 
150,000 cal/mole. 

17.8.4 Latent Thermal Injury 

In Section 17.6.7, the existence of latent or mor- 
phologically unrecognizable epidermal cellular in- 
jury after certain apparently harmless thermal ex- 
posures was proved by the repeated applications of 
sub threshold exposures. Furthermore, the time re- 
quired for recovery from these latent exposures be- 
came longer the nearer they approached the thresh- 
old of microscopic visibility. 

The concept of an unknown but definite fraction of 
certain of the cellular proteins that must be thermally 
altered in order to result in morphologically recog- 
nizable injury is in accord with these experimental 
data. 

During a heat exposure that results in latent in- 
jury, a noncritical fraction of these proteins is al- 
tered. At the termination of the heat exposure, the 
epidermis rapidly approaches normal temperature 
(Section 17.3.2) and at least partial cell function is 
resumed. Thus, during the recovery period, the ther- 
mally altered proteins are replenished to a degree 
which depends, in part, upon the length of the re- 
covery period, and, in part, upon the duration of the 
heat exposure which produced unrecognizable injury. 

17.8.5 Summary 

The numerical constants of an experimental equa- 
tion, which quantitatively predicts the morphological 
episodes incident to transepidermal necrosis, have 
been subjected to theoretical analyses. It is demon- 
strated that, of all of the known biokinetic phenomena, 
only thermal alterations in cellular proteins that have 
an energy and entropy of activation of 150 kcal/mole 
and 395 entropy units, respectively, will account for 
the experimental observations. This theory is also in 
agreement with the latent thermal injury data given 
in Section 17.6.7. 

17.9 EXPOSURE TO HOT AIR AND 
RADIANT HEAT 

17.9.1 Introduction 

In preceding sections of this chapter it has been 
shown that a very brief exposure of an animal to ex- 
cessive circumambient heat may cause rapid circula- 
tory collapse and death. It was found that transfer of 
heat to and through the skin was a more important 


cause of such casualties than was the effect of heat on 
the respiratory tract. In a quantitative and patho- 
logical study of the effects of hot water on the skin it 
was shown that certain predictable and reproducible 
reciprocal relationships exist between the intensity 
and duration of an episode of hyperthermia and its 
capacity to destroy the epidermis. 

These findings suggest that similarly reproducible 
and predictable relationships may exist between the 
intensity and duration of an episode of hyperthermia 
and casualty production by exposures to hot air and 
radiant heat such as may occur incident to a con- 
flagration or to a flame thrower attack. 

To determine whether or not such is the case a 
series of experiments was undertaken in which pigs 
received generalized cutaneous exposures for varying 
periods of time to circumambient (and circumradi- 
ant) temperatures that varied between 70 and 550 C. 
The cutaneous and systemic effects of these expo- 
sures on animals were correlated with exposure time 
and source temperature. 

17.9.2 Experimental Procedure 

Previously clipped and anesthetized pigs were 
fastened on a platform in the manner shown in Fig- 
ure 29 and a preheated oven was lowered over them. 
In most of the experiments the snout of the animal 
protruded through an aperture in the bottom of the 
platform. There were two advantages in this arrange- 
ment, one being protection of the respiratory tract 
and the other being that it was possible thereby to 
determine the time of death of animals that suc- 
cumbed during the period of exposure. 

The source of heat was a bottomless oven con- 
structed of iron and firebrick and having a capacity 
of approximately 1,100 1. The box weighed 2,700 
kg and its internal measurements were 89x91x130 
cm. Chromel alumel (10 gauge) thermocouples 
welded onto the inside plate of the box provided in- 
formation as to the source temperature during the 
period of pre-exposure heating as well as during the 
period that the animal was being exposed. To heat 
the box, it was lowered into a vertical gun annealing 
furnace^ (Watertown Arsenal). When it had become 
thoroughly heat-soaked and was at a slightly higher 
temperature than that at which it was desired to ex- 
pose the animal, the oven was quickly withdrawn 
from the furnace by an overhead crane and lowered 
over the platform on which the animal was sus- 

^ These facilities at the Watertown Arsenal were made 
available through the courtesy of the War Department. 


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355 



Figure 29. Method of exposing animals to hot air and 
radiant heat at Watertown Arsenal. Heavy iron and 
firebrick box was preheated in gun annealing furnace 
and lowered over platform. 

pended. The interval required for the descent of the 
box from the top of the tripod to the floor of the plat- 
form was between 3 and 4 seconds. 

The platform supporting the tripod upon which 
the animal was suspended was elevated 75 cm above 
the floor and covered by a layer of dry sand. In addi- 
tion to the aperture to accommodate the snout of the 
animal, there were other openings in the platform 
through which wires could be passed to the temper- 
ature recording equipment. 

Three 28 gauge iron-constantan thermocouples 
connected in parallel were fastened to the surface of 
the animal in such a way that the junctions were 
separated from the skin by a distance of between 2 
and 5 cm. These provided for a continuous recording 
of ambient temperature. 

Rectal temperatures were taken routinely. In 
some experiments a rectal thermocouple provided 
for a continuous record. In others the temperature 
was taken by thermometer before and at intervals 
after exposure. On several occasions the postexposure 


temperature of the right auricular blood was taken 
for comparison with that of the rectum. 

In a number of experiments a 28 gauge iron-con- 
stantan thermocouple contained in a venipuncture 
needle was inserted into the dermis to record the 
temperature of the subepithelial connective tissue 
during and after exposure. 

Temperature of air in different parts of exposure 
chamber: Values given in the text for ambient tem- 
perature refer to the mean temperature of the air in 
which the animal was enveloped. The thermocouples 
by which the ambient temperature was measured 
were routinely placed in approximately the same po- 
sitions in relation to the animal in all experiments. 
One was fastened to the skin just below the base of 
the tail and one on each side of the mid-portion of the 
body. It was regularly observed that the mean ambi- 
ent temperature was approximately 20 per cent lower 
than that measured by the thermocouples incor- 
porated in the wall of the exposure chamber. Al- 
though the rate of cooling of the exposure chamber 
(and the air contained by it) varied according to the 
magnitude of the initial difference between its tem- 
perature and that of the room, the drop was never in 
excess of 5 per cent in experiments lasting 15 minutes 
or less. 

Because of the convection currents that resulted 
from the difference between the temperature of the 
surface of the animal and that of the air surrounding 
it, the temperatures recorded in various parts of the 
exposure chamber showed remarkably little vari- 
ation. Thus in the mid-horizontal axis of the chamber 
difference in temperature was less than 5 per cent 
from a point 15 cm internal to the wall to a point 
15 cm external to the animal. In the mid- vertical 
axis there was less than 15 per cent difference in the 
temperature of the air between a point 15 cm below 
the roof and a point 15 cm above the floor of the ex- 
posure chamber. 

Measurement of Heat Transfer 

Under these conditions, there were three mecha- 
nisms by which heat could be transferred from the hot 
walls of the box to the surface of the animal, namely, 
air conduction, air convection, and infrared radi- 
ation. The energy transferred by conduction and con- 
vection is hereafter designated as ambient, and that 
transferred by radiation as radiant. Although the 
relative importance of these two types of heat trans- 
fer can be directly computed by means of equations 
(1) and (2) of Section 17.3, it was decided to verify 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


these calculations under the conditions that pre- 
vailed in these experiments. Unfortunately, direct 
determinations of the ambient and radiant caloric 
uptakes of animals were not feasible and it was neces- 
sary to measure these values by means of calorim- 
eters suspended in the center of the exposure cham- 
ber preliminary to animal experimentation. 

The calorimeters consisted of copper cylinders 
which measured 2.5 cm in diameter and 5 cm in 
length. One of each pair of cylinders was gold-plated 
and the other blackened with colloidal graphite 
(aquadag). Thus, the former measured only ambient 
energy, whereas the latter determined both ambient 
and radiant energy. 

The caloric uptake rate of the calorimeters was 
readily calculated from their known heat capacity 
and surface area and the experimentally determined 
rate of temperature rise as measured by an iron- 
constan tan thermocouple soldered within the calorim- 
eter. Because of the discrepancy between the size of 
these calorimeters and that of the pigs (approxi- 
mately 30x75 cm), it was necessary to multiply the 
ambient calorimetric measurements by a numerical 
factor equal to 0.5. Since the skin is known to be a 
nearly perfect black body for the radiation emitted 
under these experimental conditions and since the 
dimensions of the exposure chamber were large with 
respect to those of the animal, the radiant caloric 
measurements are directly applicable. 

Actually, these data, so corrected, apply to a 
metallic cylinder of dimensions similar to those of a 
pig. Since it has been shown that under the condi- 
tions of experimentation these data would be equally 
applicable to both smooth and rough and to metallic 
and nonmetallic surfaces, it is believed .that they 
represent a true estimation of the caloric uptake 
rate of pig skin. 

The data given in Table 18 are an estimation of 
the radiant and ambient caloric uptake rate per 
square centimeter per minute of pig skin when the 
surface temperature is 35 C. It is obvious that during 
the heat exposure the surface temperature increases 
with time, resulting thereby in a corresponding de- 
crease in the rate of caloric uptake. For skin surface 
temperatures not greater than 60 C, caloric uptake 
rates are directly proportional to the difference be- 
tween the temperature of the surrounding air and 
that of the surface of the animal. Thus, for surface 
temperatures below 60 C the requisite caloric uptake 
rates can be computed from these data. Further ex- 
amination of Table 18 shows that the infrared radi- 


ation from the inside walls of the box was the princi- 
pal source of heat energy absorbed by the animals. 
Under conditions that produced an air temperature 
of 70 C, this contribution was 50 per cent, whereas at 
500 C it was 85 per cent. These percentages remained 
nearly invariant throughout the entire time of a 
given heat exposure. As previously indicated, these 
values for the nonradiant and radiant contribution 
to caloric uptake rate can be directly computed from 
equations (1) and (2) and, if this is done, it will be 
found that they agree with the experimental values 
to within about 15 per cent. 


Table 18. Estimated caloric uptake for pig when skin 
surface temperature is 35 C. 


Air 

temperature 

C 

Caloric uptake in cal/cm^/min 
Nonradiant 

(ambient) Radiant* Total 

Per cent 
of total 
radiant 

70 

0.2 

0.2 

0.4 

50 

100 

0.5 

0.6 

1.1 

55 

150 

1.0 

1.4 

2.4 

58 

200 

1.7 

2.6 

4.3 

61 

250 

2.2 

4.2 

6.4 

65 

300 

3.0 

6.2 

9.2 

68 

350 

3.8 

9.8 

13.6 

72 

400 

4.5 

17.0 

21.5 

79 

450 

5.5 

24.0 

29.5 

81 

500 

6.5 

35.0 

41.5 

85 


* Because of the difference between the air and source temperature when 
animals are placed in the exposure chamber, these radiant data refer to a 
source temperature 20 per cent in excess of the tabulated ambient tempera- 
ture. 

17.9.3 Effects on Animals 

The results of 7 1 individual exposures of pigs are 
shown in Figure 30. It was at first intended to present 
in this chart only the data derived from 49 experi- 
ments in which pigs of uniform weight (7 to 18 kg) 
received generalized (approximately 90 per cent) 
cutaneous exposures to heat. The additional 22 ex- 
periments included those in which large animals (in 
excess of 15 kg) were used, those in which hot air was 
breathed during the time that the skin was being 
exposed, and those in which the animals were anes- 
thetized after rather than before exposure. When it 
was found that there were no significant differences 
in the experimental results that could be related to 
the body weight of the animals (7 and 32 kg) or to 
anesthesia it was decided to present all experimental 
data in one chart. 

The temperature and duration of each exposure is 
indicated by the position of the individual experi- 
ments on the grid. The vertical points of reference on 
the left are in logarithmic progression and represent 
the internal temperature of the exposure chamber. 


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357 



INDIVIDUAL ANIMALS 

• CEN. BURNING AND FATAL HYPERTHERMIA 
9 gen. BURNING (ISCHEMIC) 
e OEN. BURNING (HYPEREMIC) 

© LOCAL BURNING 
O NOT BURNED 

Figure 30. Graph showing results of 71 experiments in 
which pigs received generalized cutaneous exposures to 
ambient and radiant heat in oven. Each experiment is 
depicted by circle. Duration and temperature of ex- 
posure are indicated by position of circle in grid. 
Effect of exposure on pig is shown by character of circle. 
Curved lines traversing grid depict approximate thresh- 
olds at which varying degrees of cutaneous and sys- 
temic injury occurred. 

whereas those on the right represent the correspond- 
ing ambient temperature in the vicinity (within 5 cm) 
of the animal. The horizontal points of reference in- 
dicate the duration of the exposure period. 

It may be seen that the experiments fall into three 
main groups with respect to their effects on the pigs. 
Some animals were unharmed and developed neither 
superficial nor systemic evidence of injury, others re- 
ceived cutaneous injury with insufficient systemic 
disturbance to result in early collapse and death, and 
still others died during the exposure or within 30 min- 
utes after the exposure. 

The upper limits of exposures which pigs survived 
without either cutaneous injury or severe physiologi- 
cal disturbance are indicated by the line (I) that 
traverses the grid from left to right. Exposures lying 
below this line failed to cause cutaneous burning. 
Exposures lying between the first and second lines 
characteristically resulted in mild or localized burn- 


ing. The second line (II) represents the approximate 
threshold at which generalized second-degree burning 
occurred. The third line (III) represents the approxi- 
mate threshold at which the burned skin and sub- 
cutaneous tissue underwent ischemic coagulation. 
The skin of most pigs that received exposures lying 
above this threshold was pale and the loss of elas- 
ticity of the coagulated superficial tissues resulted in 
the formation of deep fissures when the extremities 
were flexed. The uppermost line (IV) represents the 
approximate threshold at which rapidly fatal sys- 
temic hyperthermia occurred. Most pigs receiving 
exposures in excess of this threshold died within a 
few minutes (usually under 15 and occasionally as 
long as 30) after the oven had been lifted from the 
platform. 

Comparison of effects of hot air and hot water ex- 
posures: Injury by heat is determined by the degree 
and duration of the rise in tissue temperature. It will 
be shown that for the same kind of skin the produc- 
tion of a given degree of thermal injury depends only 
on the time-temperature relationships within the 
tissue irrespective of the source of the heat. Since 
threshold II in the hot air experiments (see Figure 30) 
depicts the occurrence of transepidermal necrosis, it 
can be inferred that for the same source temperature 
actual tissue temperatures attained were consider- 
ably lower than those in hot water experiments (see 
Figure 14). 

In Figure 31 are depicted the source temperature- 
time relationships that were required to produce 
transepidermal necrosis in both the air and water ex- 
posures, where in the latter case the surface of the 
skin was maintained at essentially the same temper- 
ature as that of the source. A comparison of the two 
curves shows that a 15-minute exposure to water at 
48 C was sufficient to produce approximately the 
same degree of injury as that which resulted from a 
15-minute circumambient and radiant exposure at 
75 C. A hot water exposure for 1 minute at 53 C pro- 
duced about the same degree of injury as resulted 
from a 1 -minute exposure at 160 C to ambient and 
radiant heat. It is apparent, therefore, that the actual 
surface temperatures responsible for the kind of irre- 
versible injury observed at threshold II in Figure 30 
were considerably lower than the recorded ambient 
temperatures at which they were produced. In the 
hot water exposures the change in tissue temperature 
with time was determined by the rate of heat flow 
through the skin, whereas in the oven exposures it 
was limited by the rate of heat transfer to the surface. 


THRESHOLDS OF INJURY 

acute hyperthermic OEATH 

gen. burning (ISCHEMIC) 

gen. burning (hyperemic) 

LOCAL BURNING 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 



Figure 31. Solid curve depicts time-source temperature 
relationships requisite to complete transepidermal 
necrosis when skin site is exposed to flowing water of 
constant temperature. Dotted curve shows time-air 
temperature relationships (curve II of Figure 30) that 
produce similar degree of injury when skin surface is 
surrounded by an envelope of radiant and ambient heat 
(oven experiments). Open circles show values which 
were computed by means of equations (1), (2), (Section 
17.3) and (15) (Section 17.7). 

The actual time-temperature relationships within 
the epidermis under these experimental conditions 
have been computed by equation (6), which results 
from the application of the general theory of heat to 
this problem (Section 17.3.1), and are reported in 
Table 7B (Section 17.3.2). These data show the rate 
of increase in the epidermal temperature incident to 
an exposure to an envelope of radiant and ambient 
heat. It is apparent in the case of a generalized ex- 
posure that long before the temperature of the sur- 
face of the skin would approach that of the air, the 
animal would have succumbed to a generalized hy- 
perthermia. 

In Section 17.6.5, the degree of epidermal destruc- 
tion was shown to be mathematically predictable by 
means of equation (15), so long as T t, the time de- 
pendence of the basal epidermal temperature, is 
known. This equation was developed empirically 
from data pertaining to the degree of epidermal in- 
jurj^ when the skin surface was immediately brought 
to and maintained at a constant temperature (hot 
water experiments). It was stated that equation (15) 
should predict the time required to produce all ther- 
mally induced transepidermal injuries which result 
from any conceivable type of heat application, so 
long as the time dependence of the temperature at 
the dermal-epidermal junction during the heat ex- 
posure is known. 

The five circles depicted in Figure 31 are the result 


of numerically integrating equation (15) following 
the substitution of the epidermal time-temperature 
relationships which result from an exposure to ambi- 
ent and radiant heat as computed by equation (6) 
and recorded in Table 7B. These calculations were 
made for air temperatures of 80, 100, 125, 150, and 
175 C, respectively. It is to be observed that the con- 
cordance of these computations with the experi- 
mental data is excellent. Considerable confidence can 
thus be placed both in the statement of the previous 
paragraph and in the ‘‘infinite body picture’’ (Sec- 
tion 17.3.1) which permitted the estimation of the 
temperatures attained in the epidermis as a function 
of time. 

Probable Effects of Comparable Exposures 
ON Man 

So far as the skin effects of ambient and radiant 
heat are concerned, the reactions in man and pig 
should be similar if the time-temperature relation- 
ships within the epidermis were the same in each in- 
stance (see Figure 14, Section 17.6.4). However, a 
predictable difference in these relationships during 
identical heat exposures of this type arises from the 
fact that sweating of human skin can undoubtedly 
increase the time threshold at which cutaneous burn- 
ing occurs. 

That sweating can afford considerable protection in 
the case of relatively low-intensity hot air exposures 
can be assumed from the fact that man may lose 
moisture by this mechanism at the rate of approxi- 
mately a liter per hour. This could result in heat loss 
at the rate of between 0.5 to 1.0 cal/min/cm^ of skin 
surface. Heat loss by porcine skin through vaporiza- 
tion of moisture is relatively slight (approximately 
0.1 cal/cmVmin). See Section 17.5. Thus, in view of 
the caloric uptake data presented in Table 18, it is 
possible that the time threshold for cutaneous burn- 
ing in man is appreciably longer than that for the pig 
for all circumambient and radiant temperatures 
lower than about 120 C. That such a degree of pro- 
tection would be afforded at higher air temperatures 
is unlikely since it would be necessary to assume that 
sweating was already established at a significant level 
at the moment of exposure and that all of the sweat 
excreted was vaporized. No experiments were con- 
ducted to establish the quantitative extent to which 
sweating may be capable of protecting human skin 
against thermal injury to either low or high ambient 
and/or radiant temperatures. 

It should be emphasized that these data refer only 


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EXPOSURE TO HOT AIR AND RADIANT HEAT 


359 


to unclothed animals. It is possible to estimate the 
degree of protection afforded by clothing by a knowl- 
edge of their impedance to the heat reaching the skin 
surface, but since this thermal impedance is so de- 
pendent upon the physical characteristics of the 
fabrics involved, upon tightness of fit, and upon the 
type of heat exposure, further consideration of this 
problem is not warranted in this chapter. The method 
of obtaining these thermal protectivities of clothing 
under specific experimental conditions is given in 
detail else where. 

Death of Pigs ‘ 

It may be seen from Figure 30 that rapidly fatal 
physiological disturbances resulted from a wide range 
of thermal exposures and that at any given temper- 
ature within the range investigated survival or death 
was determined by the duration of the exposure 
period. Observations were made on the various patho- 
logical and physiological changes resulting from sub- 
lethal and lethal cutaneous exposures to heat. 

Pathological Changes 

There was no apparent relationship between the 
occurrence of early death and the severity of the cu- 
taneous injury. Some animals that died during or 
soon after exposure at relatively low temperatures 
showed remarkably little evidence of cutaneous in- 
jury. Others that received extensive third-degree 
burns at higher temperatures survived many hours 
after exposure and showed no systemic evidence of 
impending death at the time they were sacrificed. It 
was obvious that the cutaneous lesion per se was not 
responsible for early collapse and death. 

Apart from cutaneous burning there were no sig- 
nificant differences in the pathological changes ob- 
served in animals that died following short exposures 
at high temperatures and in those that died following 
longer exposures at lower temperatures. The most 
constant post-mortem finding in all animals that 
died within 30 minutes after exposure to heat was the 
presence of widely disseminated small and large 
focuses of hemorrhage throughout the internal vis- 
cera. These were seen most frequently and promi- 
nently beneath the endocardium of the right and 
left ventricles. Another site of predilection for such 
hemorrhages was the gastric and duodenal mucosa. 

The right auricle was characteristically dilated and 

* Several goats and dogs received exposures estimated to be 
lethal or sublethal for pigs and the impression was gained that 
their susceptibility to fatal systemic hyperthermia did not 
differ significantly from that of the pig. 


filled with dark red unclotted blood. The impression 
was gained that the ventricles were more frequently 
found in the state of contraction after high- than 
after low-intensity exposures. 

The lungs of pigs that died during or soon after 
cutaneous exposures to excessive heat rarely showed 
more than a mild degree of pulmonary edema, in con- 
trast to those of dogs and goats, in which systemic 
hyperthermia characteristically led to moderate or 
severe pulmonary edema. 

Animals sacrificed 12 to 24 hours after severe cu- 
taneous burns had been sustained frequently showed 
severe parenchymatous degeneration of adrenal 
cortex, liver, and renal tubular epithelium. Hemo- 
globin casts were sometimes observed in the collect- 
ing tubules of the kidneys and the urine of burned 
animals regularly contained large amounts of blood 
pigment. 

Changes in Blood 

Examination of the blood of burned animals regu- 
larly showed intravascular hemolysis. That intra- 
vascular hemolysis was not a determining factor in 
survival was indicated by its absence in animals that 
died after low-intensity exposures. A more complete 
discussion of the relationship between intensity of 
thermal exposure and hemolysis Avill be found in 
Section 17.10. 

Examination of wet and dry smears of blood of 
severely burned animals disclosed microspherocytosis 
and disintegration of erythrocytes (see Figure 32). 
These changes were similar to those observed in the 
blood of burned human subjects, by Shen, Ham, and 
Fleming.^2 They were not observed in the blood of 
animals that died after low-intensity thermal ex- 
posures. In severely burned animals there was an 
increase both in the clotting time and in the fragility 
of erythrocytes. 

Plasma Turbidity. The observation of turbidity of 
the plasma together with the finding in some fatally 
burned animals of small agglomerates of protein and 
enmeshed cells in wet smears of blood led to a re- 
investigation of a phenomenon described by Rabat 
and Levine. These observers reported that the in- 
travenous injection into a cat of 4 ml of heated cit- 
rated plasma caused immediate death. After cen- 
trifugalization, they found that the supernatant 
fluid of such plasma produced no ill effects, whereas 
death resulted from the intravenous injection of the 
resuspended sediment. 

A repetition of the experiments of Rabat and 


SECRET 


360 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 



A B 


Figure 32. Blood smears of pig No. 856 (9.1 kg) be- 
fore (A) and 3 minutes after (B)5-mmute exposure to hot 
air and radiant hpat at ambient temperature of 180 C. 
Animal received third-degree burns of about 85 per cent 
of body surface and died 3 minutes later with rectal 
temperature of 43.5 C. Examination disclosed intra- 
vascular hemolysis, plasma potassium concentration of 
19.4 milliequiv/1 and disintegration of erythrocytes as 
shown in (13). During exposure, temperature at inter- 
face between dermis and subdermal fat, as recorded by 
needle thermocouple, rose to maximum of 63 C. 

Levine resulted in the observation that blood pres- 
sure fell rapidly and that sometimes animals died 
following the intravenous injection of a small amount 
of heated citrated plasma. However, when heparin 
was used as an anticoagulant instead of citrate, ani- 
mals tolerated relatively large intravenous injections 
of heated plasma without ill effects and without sig- 
nificant change in blood pressure. Slight lowering of 
blood pressure was observed in a few animals after 
injection of heated heparinized plasma or the sedi- 
ment of heated plasma. No deaths occurred, how- 
ever, even when amounts as great as 15 ml were used. 

It was concluded that the particulate masses in 
preheated blood described by Rabat and Levine may 
be deleterious to a slight degree and in combination 
with sodium citrate (250 mg/10 ml of blood) may 
cause death if injected rapidly. It is not believed, 
however, that these masses contributed significantly 
to the hyperthermic deaths observed in these ex- 
periments. 

Perfusion Experiments. A heart-lung preparation 
(Starling method) was perfused with the blood of a 
dog that had died of circulatory failure 7 minutes 
after being immersed in hot water at 70 C. Continu- 
ous records of the heart-lung preparation included 


aortic pressure (Hg manometer), systemic minute 
output (total output less coronary flow), ventricular 
volume (Henderson cardiometer with a Kiese volume 
recorder), and oxygen consumption (spirometer). 

The preparation had been used earlier for a study 
of the metabolic effects of alloxan; the heart was 
failing spontaneously at the time the blood from the 
burned animal was introduced into the perfusing 
system (about 3 hours after the preparation had been 
isolated). Fifty milliliters of the blood of the heated 
animal were injected into the venous return during 
a period of 1 minute. The minute output was about 
130 ml/min at the time of the injection and the in- 
jected blood reached the heart diluted two or three 
times with the original blood of the preparation. 

Six minutes later 100 ml of the blood of the burned 
animal were injected again in a period of 1 minute. 
This was diluted no more than once with the blood of 
the preparation. 

Six minutes later the blood in the venous reservoir 
was removed and replaced with 200 ml of blood of 
the burned animal. Following this last addition the 
heart-lung preparation was being perfused almost 
entirely by the blood of the heated animal. 

In none of the three trials was there any significant 
change in the pressure, the minute output, the heart 
rate, or the oxygen consumption. Although coronary 
flow was not recorded, any great increase in it such 
as might have been expected if the blood had con- 
tained as much as 0.5 mg of histamine would have 
been recognized by an increase in the discrepancy 
between the stroke volume as recorded by the cardi- 
ometer and the stroke volume as calculated from 
minute output and heart rate. Such a change was not 
observed. 

No deleterious effect resulted from perfusing the 
heart-lung preparation with the blood of the burned 
dog. Actually there was slight evidence of a beneficial 
effect, such as would be expected from the addition 
of any fresh blood after 3 hours of perfusion. 

Relation of Systemic Hyperthermia to Survival 

There appeared to be a definite correlation be- 
tween survival and the height to which the internal 
body temperature was raised. Most of the animals 
that died soon after exposure were found to have a 
marked elevation of rectal temperature. In the case 
of exposures of long duration and low intensity the 
rectal temperature was only slightly lower than that 
of the blood within the right auricle. In animals that 
died within a few minutes after exposures of short 


SECRET 


EXPOSURE TO HOT AIR AND RADIANT HEAT 


361 


duration and high intensity there was characteristi- 
cally a difference of several degrees between rectal 
and blood temperature (see Section 17.11). 

The correlation between severity of systemic hy- 
perthermia and the occurrence of early death is 
shown in Figure 33. With one exception all pigs that 



Figure 33. Distribution of animals according to maxi- 
mum 30-minute rise in rectal temperature following 
exposure to hot air and radiant heat. Initial tempera- 
tures were low because of pentobarbital sodium an- 
esthesia. Open portions of columns represent animals 
that survived; shaded portions, animals that died dur- 
ing or within 30 minutes after exposure. It is apparent 
that there is close correlation between systemic hyper- 
thermia and death. 

died during the early postexposure period were those 
that developed rectal or heart’s blood temperatures 
of 42.5 C or higher. No pig whose rectal temperature 
rose to 44 C or higher survived for more than a few 
minutes. Eleven of the 15 that developed rectal 
temperatures between 43 and 44 C and 4 of the 13 
with rectal temperatures between 42 and 43 C died 
during the episode of hyperthermia. 


Pathological Physiology ^ 

Prior to the exposure of several pigs to hot air, in- 
sulated electrocardiographic leads were connected 
with the extremities and a carotid cannula was in- 
troduced. The effect of the exposure on the rate of 
respiration, the pulse rate, the arterial blood pres- 
sure, and the conduction system of the heart of 
these animals was observed. 

Within a few seconds after exposure, there was a 
sharp increase both in blood pressure and in rate of 
respiration. The respiratory rate continued to in- 
crease and remained rapid for some time after the 
exposure Avas terminated. Soon after the initial rise 
there was a fall in blood pressure to or slightly below 
the pre- exposure level. In some animals, the pressure 
was well maintained at that level until within a few 
minutes before death, whereas, in others, there was a 
gradual and progressive decline beginning immedi- 
ately at the conclusion of the initial rise. Inability to 
control the movements of the animal during the 
period of exposure made it impossible to secure satis- 
factory records of venous pressure. 

Electrocardiographic abnormalities were observed 
in some animals soon after the beginning of exposure, 
Avhereas, in others, such changes did not develop un- 
til well after the onset of circulatory failure. Abnor- 
malities observed in a few instances soon after the 
beginning of the exposure (within 2 or 3 minutes) in- 
cluded increase in rate, reduction in the voltage of 
the QRS complex, and inversion of the T waves. 
Ventricular extra-systoles were observed and as the 
exposure was prolonged there were greater disturb- 
ances in rhythm. Such animals developed ventricular 
tachycardia followed by fibrillation and death. 

Although abnormalities in the electrocardiogram 
were sometimes observed before there was evidence 
of respiratory failure, the terminal and agonal fall in 
blood pressure usually occurred at about the same 
time that tachypnea gave way to intermittent peri- 
ods of apnea. 

Although the results of these experiments indicated 
that there were two types of hyperthermic circula- 
tory failure, one central and the other peripheral, it 
was obvious that further and more rigidly controlled 
physiological experimentation was required. Such 
studies were not feasible in the circumstances in 
which the hot air experiments were conducted (see 
Section 17.11). 

Changes in Blood Potassium. Samples of blood were 
withdrawn by cardiac puncture before, during, and 
after lethal exposures of four pigs to hot air. It was 


SECRET 


362 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


found that the potassium concentration of pig’s 
blood is approximately 50 milliequiv/1. The partition 
of potassium between erythrocytes and plasma is 
approximately 50 to 1.5. The postexposure plasma 
levels in these four animals were 7.3, 10.6, 17.4, and 
19.6 milliequiv/1, respectively. The observation that 
cutaneous hyperthermia was capable of causing the 
plasma potassium to rise to 17 milliequiv/1 and 
higher suggested acute potassium poisoning as a po- 
tential cause of death. Further investigation of the 
importance of potassium release to the occurrence of 
circulatory failure and death following exposure to 
heat will be discussed in Sections 17.10 and 17.11. 

17.9.4 Summary 

The time-temperature relationships responsible 
for varying degrees of cutaneous injury and for acute 
circulatory collapse and death incident to exposures 
to circumambient and circumradiant heat similar to 
those that may result from a conflagration or from a 
flame thrower attack have been determined for the pig. 

At relatively low air temperatures (under 120 C) 
man, because of his ability to sweat, is undoubtedly 
less susceptible to injury than the pig. It is doubtful, 
however, that sweating provides a significant degree 
of protection at higher temperatures in which the 
rate of heat transfer to the skin is considerably more 
rapid than the rate at which it can be dissipated by 
vaporization of sweat. 

It should be borne in mind that the relationships 
of source temperature to injury production derived 
from these experiments apply to unprotected skin 
and are not valid for exposures in which the skin is 
protected by hair or clothing. 

It has been shown that the time-tissue tempera- 
ture relationships responsible for transepidermal 
necrosis (second-degree burning) by exposure to hot 
water as given in equation (15) (Section 17.6) are 
equally applicable to exposures to circumambient 
and circumradiant heat. 

The severity of the immediate physiological dis- 
turbances resulting from exposure to excessive heat 
is frequently disproportionate to the severity of cu- 
taneous burning. Rapid circulatory collapse and 
death may result from exposures of such low intensity 
that little or no burning of the skin is sustained. Ex- 
posures of short duration at higher temperatures may 
cause severe and generalized cutaneous burning with 
remarkably little systemic physiological reaction 
during the early postexposure period. 

']''he severity of the immediate physiological dis- 


turbances resulting from exposure to excessive heat 
bears a quantitative relationship to the extent to 
which the body temperature is increased. Pigs in 
which the rectal temperature failed to rise above 
42 C rarely and those in which it rose as high as 44 C 
invariably died of acute circulatory failure. In ani- 
mals that died within a few minutes after exposure 
to excessively high environmental temperatures, the 
temperature of heart’s blood was consistently higher 
than that recorded by a rectal thermometer. The 
shorter the interval between onset of exposure and 
death, the greater was the difference between the 
temperature in the rectum and that in the heart. 

Although the precise physiological mechanisms re- 
sponsible for hyperthermic circulatory failure were 
not fully elucidated by these experiments, it was ap- 
parent that the early death of some burned animals 
was caused or contributed to by hyperpotassemia. 

Perfusion experiments failed to disclose the pres- 
ence of injurious humoral agents (other than po- 
tassium) in the blood of recently burned animals. 

Pathological examination of the bodies of animals 
that died during or soon after an episode of acute 
systemic hyperthermia disclosed evidence of capil- 
lary endothelial damage in the form of disseminated 
visceral petechiae. Intravascular hemolysis and al- 
terations in the form and fragility of erythrocytes 
were observed in animals that had sustained severe 
cutaneous burning. 

17.10 HYPERPOTASSEMIA CAUSED BY 
EXPOSURE TO HEAT 

17.10.1 Introduction 

In Section 17.9, it was observed in some experi- 
ments that cutaneous exposure of pigs to excessive 
heat resulted in rapidly fatal circulatory failure that 
was associated with marked electrocardiographic ab- 
normalities and a sharp rise in plasma potassium to 
levels ordinarily considered incompatible with life. 

The implication of these observations was such as 
to warrant further study of the effect of cutaneous 
hyperthermia on the concentration of potassium in 
the blood. 

17.10.2 Experimental Procedure 

Samples of blood for chemical analysis were ob- 
tained from the heart by means of an inlying jugular 
cannula. 

Potassium determinations were carried out on the 
trichloroacetic acid filtrate of plasma and lysed 
blood according to the method of Lowry and Hast- 


SECRET 


HYPERPOTASSEMIA CAUSED BY EXPOSURE TO HEAT 


363 


ings as modified by Cohn and Tibbetts. Hema- 
tocrit was determined in Wintrobe tubes after cen- 
trifuging for 30 minutes at 2500 rpm. The method of 
Bing,^^ et al, as modified by Ham,^'^ was used for de- 
termining plasma hemoglobin. Whole blood hemo- 
globin was determined on 0.1 ml of 1/5 dilution of 
blood in 5 ml of dilute ammonia by the Klett-Sum- 
merson colorimeter. 

17.10.3 Animal Experiments ^ 

Before undertaking further investigation of the 
relationship of hyperthermia to the development of 
hyperpotassemia, an experiment was undertaken to 
determine the effect of systemic anoxia on the po- 
tassium concentration of the plasma independently 
of hyperthermia (Table 19). 

Table 19. Changes in the blood of a pig during and after 
death by strangulation. 

Hemoglobin 

in 

Vol- Hemo- plasma 

Blood ume globin % Potassium Potassium 

with- packed in cells hemoly- in red cells in plasma 
drawn cells g/100 ml sis milliequiv/1 milliequiv/1 


Control 

45 

33 

0 

132 

5.2 

0 min 

4 min 

49 

31 

Trachea clamped 

0 

128 

9.1 

8 min 

48 

34 

0 

130 

9.3 

8 min 

68 min 

? 

? 

Animal died 

0 

? 

16.8 


A control sample of blood was taken from an 8.2-kg 
pig. The trachea was then exposed and clamped and 
after 4 and 8 minutes additional samples of blood 
were obtained. The animal died at the end of 8 min- 
utes and was allowed to remain on the operating 
table at room temperature for an hour thereafter, at 
which time, the fourth and last sample of blood was 
withdrawn. The anal3rtical results are shown in 
Table 19. 

It may be seen that the plasma potassium level 
was almost doubled during the 8 minutes that elapsed 
between the onset of asphyxia and death. Most of the 
increase occurred during the first 4 minutes of this 
period. There are two obvious sources from which the 
increment may have been derived, one being the 
erythrocytes and the other the extra vascular tissue. 
A comparison of hematocrit and hemoglobin content 
of cells at the end of the 4-minute period indicates 
that swelling of erythrocytes had occurred. The 
hematocrit rose from 45 to 49, whereas the hemo- 
globin dropped from 33 to 31 g per 100 ml of cells. It 


appears that the observed decrease in the concen- 
tration of intracellular potassium from 132 to 128 mil- 
liequiv/1 was probably due to swelling of red cells 
rather than to loss by leakage. Since the actual po- 
tassium content of the erythrocytes did not appear 
to have dropped and since there was no hemolysis, it 
was inferred that the potassium in the plasma had 
been increased by diffusion from extravascular 
sources. 

The need for taking blood promptly after death, if 
reliance is to be placed on analytical results, is illus- 
trated by the rise in plasma potassium that occurred 
during the first hour post mortem. At death, the 
plasma concentration of potassium was 9.3 milli- 
equiv/1, whereas 1 hour later it was 16.8. Although 
there is no evidence in the data presented in Table 19 
as to the source of this increment, other observations 
indicated that both leakage from red blood cells and 
diffusion from extravascular tissues may cause a 
post-mortem rise in plasma potassium. So far as the 
significance of this experiment in providing control 
data is concerned, it is apparent that a twofold rise 
in plasma potassium may occur as a result of severe 
systemic anoxia. 

In order to correlate chemical data with known 
degrees of cutaneous hyperthermia, it was decided 
to submerge animals in hot water rather than expose 
them to hot air. By the former method, the tempera- 
ture of the surface of the skin could be controlled 
with greater precision than was possible by the latter. 

The experimental procedure that was followed in 
submerging animals in hot water is described in de- 
tail in Section 17.11. The animals were anesthetized 
with pentobarbital sodium and between 60 and 75 
per cent of the total body surface was raised to the 
desired level. The effects on the blood of exposing 
four pigs to water at 47 C and eight pigs to water 
at 75 C are shown in Table 20. 

Exposure at 47 C: Although all these animals de- 
veloped an acute and rapidly fatal systemic hyper- 
thermia, none showed a rise in plasma potassium sig- 
nificantly greater than that which may result from 
anoxia independently of hyperthermia. In none of 
these was the magnitude of the increase comparable 
to that which was observed in some of the severely 
burned animals reported in Section 17.9. 

In the first two animals, it appeared that the po- 
tassium increase in the plasma was derived from ex- 
travascular sources. In the third animal the increase 
was due to leakage in only one sample. In the fourth 
animal it may have been due in part to leakage from 


SECRET 


364 STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


intact erythrocytes, 

and in 

part to diffusion from 

kind produced 

in these animals did not result in a 

extra vascular tissue. 

Cutaneous hyperthermia of the 

significant amount of intravascular hemolysis. 





Table 20. 

Effects on the blood of exposing pigs to hot water. 















Potassium in plasma — milliequiv/1 










Hemoglobin 





Increment 







Blood 


Hemo- 

in Potassium 



Potential 

from 



Thermal 

Body 

Time 

samples 

Volume 

globin 

plasma 

in red 



increment 

sources 

Pig 

Time 

exposure 

temp 

of 

time 

packed 

in cells 

% hemol- 

cells 



from 

other than 

No. 

min 

C 


C 

death 

taken 

cells 

g/100 ml 

ysis milliequiv/1 

Total 

Change 

hemolysis hemolysis 

877 

Control 



34.3 


Control 

32 

29 

0 

145 

3.8 

• • • • 

... 

... 


0 

Started 














10 





10 min 

33 

30 

0. 

158 

6.2 

+2.4 

0 

2.4 


14 


\47 


. . 

14 min 

33 

30 

0. 

154 

6.9 

+3.1 

0 

3.1 


24 



44.3 


24 min 

31 

32 

0. 

158 

8.2 

+4.4 

0 

4.4 


26 

Stopped 


. . . 

+ 







.... 


. . . 

1057 

Control 



37.0 


Control 

35 

35 

0.1 

115 

4.4 


. . . 

• • • 


0 

Started ] 














20 


►47 



20 min 

36 

35 

0.0 

125 

7.0 

+2.6 

0 

2.6 


36 

Stopped^ 


45.5 

+ 

36 min 

36 

35 

0.2 

120 

10.2 

+5.8 

0.2 

5.6 

1056 

Control 



37.8 


Control 

33 

37 

0.1 

118 

4.7 

.... 

. . . 



0 

Started 














10 



• • • 


10 min 

33 

36 

0.1 

114 

5.9 

+ 1.2 

0 

1.2 


15 


\47 



15 min 

35 

35 

0.1 

113 

7.2 

+2.5 

0 

2.5 


34 





34 min 

36 

35 

0.2 

118 

7.1 

+2.4 

0.1 

2.3 


45 

Stopped 


45.5 

+ 





. . . 


— 



923 

Control 



? 

, . 

Control 

48 

33 

0.0 

? 

3.8 

.... 

. . . 

. • • 


0 

Started 














13 





13 min 

47 

44 

0.1 

124 

5.5 

+1.7 

0.1 

1.6 


23 




, . 

23 min 

46 

46 

0.2 

120 

5.5 

+ 1.7 

0.2 

1.5 


34 


47 

. . . 


34 min 

55 

32 

0.1 

113 

6.2 

+2.4 

0.2 

2.2 


42 





42 min 

55 

32 

0.1 

112 

6.5 

+2.7 

0.2 

2.5 


47 




, . 

47 min 

56 

33 

0.1 

? 

7.5 

+3.7 

0.2 

3.5 


50 

Stopped^ 


? 

+ 







— 



899 

Control 



37.4 

, , 

Control 

38 

34 

0.4 

139 

3.6 

.... 


. • • 


0 

Started 1 

i75 













1 

Stopped] 

r 













5 

• • • • 



, , 

5 min 

48 

31 

3.6 

109 

10.2 

+6.6 

3.7 

2.9 


16 

• • • • 




16 min 

37 

33 

8.6 

117 

6.9 

+3.3 

6.5 

• • • 


46 

• • • • 


. . . 

, , 

46 min 

39 

32 

7.5 

118 

4.2 

+0.6 

6.2 

. . • 


76 

.... 


39.2 

. . 

76 min 

37 

35 

6.7 

122 

7.4 

+3.8 

5.2 

. . . 

918 

Control 



36.6 

* , 

Control 

34 

44 

0.0 

131 

3.7 

• . • • 

• • • 



0 

Started ^ 

I 75 













3 

Stopped^ 

r 













4 



. . . 


4 min 

51 

30 

2.5 

98 

11.0 

+7.3 

2.6 

4.7 


11 





11 min 

45 

42 

4.4 

110 

9.5 

+5.8 

4.2 

1.6 


17 



. . . 

. , 

17 min 

44 

35 

5.9 

102 

9.5 

+5.8 

5.1 

0.7 


37 



40.6 


37 min 

40 

48 

5.6 

103 

9.4 

+5.7 

4.0 

1.7 


55 



. . . 

+ 




. . . 



— 



919 

Control 




. . 

Control 

45 

33 

0.8 

118 

4.2 

.... 


. . . 


0 

Started 


37.1 








.... 


. . . 


4 


•75 


. . 

4 min 

56 

29 

7.8 

81 

25.5 

+21.3 

8.6 

12.7 


5 

Stopped 














8 




. . 

8 min 

47 

26 

25.5 

67 

21.4 

+ 17.2 

20.2 



10 



. . . 


10 min 

40 

32 

22.2 

? 

18.3 

+14.1 

? 

. . . 


14 





14 min 

35 

37 

23.1 

77 

17.0 

+ 12.8 

12.6 

. . . 


17 



44.3 

. . 

17 min 

33 

31 

30.1 

72 

17.5 

+ 13.3 

15.2 

. . . 


18 



. . . 

+ 










913 

Control 



38.6' 

, , 

Control 

26 

37 

0.0 

116 

3.5 

.... 

. . . 

. . . 


0 

Started 

1 













2 




, , 

2 min 

35 

32 

12.3 

103 

14.2 

+ 10.7 

7.7 

3.0 


6 


75 

r 



6 min 

32 

33 

24.5 

96 

17.7 

+ 14.2 

14.7 



7 

Stopped 

) 













8 

.... 


40.8 

+ 

8 min 

30 

32 

25.3 

111 

17.4 

+ 13.9 

16.0 

. . . 

907 

Control 



37.3* 


Control 

42 

34 

0.6 

125 

3.5 

.... 


. . . 


0 

Started 














8 


^75 

• • • 


8 min 

53 

31 

2.7 

100 

17.4 

+ 13.9 

3.1 

10.8 


10 

Stopped 

j 

42.5* 

+ 






... 

— 




* Right heart temperature. 


SECRET 


HYPERPOTASSEMIA CAUSED BY EXPOSURE TO HEAT 


365 


Table 20 {Continued). 


Potassium in plasma — milliequiv/1 
Hemoglobin Increment 








Blood 


Hemo- 

in 

Potassium 



Potential 

from 



Thermal 

Body 

Time 

samples 

Volume 

globin 

plasma 

in red 



increment 

sources 

Pig 

Time 

exposure 

temp 

of 

time 

packed 

in cells 

% hemol- 

cells 



from 

other than 

No. 

min 

C 


C 

death 

taken 

cells 

g/100 ml 

ysis 

milliequiv/1 

Total 

Change 

hemolysis hemolysis 

910 

Control 



36.8 


Control 


0 

? 


3.0 





0 

Started 














2 





2 min 


? 

? 


19.1 

+ 16.1 




5 


>75 



5 min 


? 

? 


18.1 

+ 15.1 




7 




7 min 


? 

? 


24.0 

+21.0 




13 




+ 











14 

Stopped^ 


43.7 


14 min 





17.3 

+ 14.3 



908 

Control 



? 


Control 

32 

? 

? 

106 

3.8 





0 

Started ’ 














4 





4 min 

? 

? 

? 

? 

16.7 

+ 12.9 




9 


75 



9 min 

33 

? 

? 

98 

18.5 

+14.7 




11 





11 min 

32 

? 

? 

90 

17.1 

+13.3 




14 

Stopped^ 


? 

+ 










912 

Control 



36.0 


Control 

33 

37 

0.0 

125 

4.1 





0 

Started 














1 





1 min 

45 

31 

1.9 

102 

16.7 

+ 12.6 

1.6 

11.0 


4 


>75 



4 min 

33 

37 

19.2 

? 

? 

? 

? 



5 




5 min 

34 

34 

24.2 

100 

16.4 

+12.3 

16.5 



10 





10 min 

40 

31 

19.9 

85 

16.4 

+12.3 

14.2 



14 

Stopped^ 


43.1 

+ 











Exposure at 75 C: The chemical changes in this 
group were of a different order of magnitude from 
those observed in animals exposed at 47 C. All ani- 
mals exposed for 5 minutes, or longer, at 75 C de- 
veloped plasma potassium levels in excess of 16 milli- 
equiv/1. In most instances, such levels were reached 
during the first few minutes of exposure and were 
either maintained or increased as the period of ex- 
posure was prolonged. If the pig survived for more 
than a few minutes after the termination of the ex- 
posure, there was a slow decline in plasma potassium 
concentration. Thus, in animal 919 the plasma po- 
tassium rose from 4.2 to 25.5 milliequiv during the 
first 4 minutes of exposure, and during the next 
4 minutes declined to 17.4. 

The rapidity with which an excessively high 
plasma potassium level may be lowered by extra- 
vascular diffusion is indicated by the discrepancies 
that were observed between estimated increments 
by hemolysis and total amounts present. Thus, it 
may be seen in the case of pig 913 that with an incre- 
ment by hemolysis of 7 milliequiv/1 between the 2- 
and 6-minute samples, the actual plasma level rose 
by only 3.5 milliequiv. Similarly, in pig 912 the in- 
crement by hemolysis between the 1- and 5-minute 
samples was 14.9 milliequiv/1, whereas the total 
plasma potassium actually changed from 16.7 to 16.4 
during this period. 

In most of the animals exposed at 75 C, there was 
some increase in the volume of packed cells. The 


comparison of cell volume and hemoglobin content 
indicated that most, if not all, of the early increase in 
cell volume was due to swelling of erythrocytes 
rather than to loss of plasma or mobilization of cells 
from storage depots. 

It is of interest to note that plasma hemoglobin 
values as high as 24 per cent hemolysis were observed 
as early as 5 minutes after the onset of cutaneous 
hyperthermia. It was estimated that during this 
period the temperature in the vicinity of the most 
superficial blood vessels probably rose to approxi- 
mately 70 C. 

Chemical changes in the blood of dogs caused by 
cutaneous hyperthermia: It was inferred from the 
foregoing experiments on pigs that most of the po- 
tassium responsible for these potentially fatal plasma 
levels either leaked out of intact red blood cells or 
escaped from hemolyzed cells. If this inference is cor- 
rect, fatal hyperpotassemia due to cutaneous hyper- 
thermia would occur only in animals having a high 
concentration of potassium in the erythrocytes, such 
as man or pig. Its occurrence could not be expected 
in an animal having a low cellular concentration of 
potassium, as is the case in dog’s blood. 

To test this assumption, samples of blood were 
taken from each of five dogs before and during im- 
mersion in hot water. The results of these experi- 
ments are shown in Table 21. 

The animals were exposed at temperatures ranging 
between 55 and 75 C until death occurred. The high- 


SECRET 


366 STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 





Table 21. 

Changes 

in blood of dogs caused by immersion in hot water. 



Dog 

No. 

Time 

in 

min 

Thermal 

exposure 

C 

Body 

temp 

C 

Time 

of 

death 

Blood 

samples 

time 

taken 

Volume 

packed 

cells 

Hemoglobin 
in cells 
g/100 ml 

Hemoglobin 
in plasma 
% hemolysis 

Potassium 
in red cells 
milliequiv/1 

Potassium 
in plasma 
milliequiv/1 

931 

Control 



35.4 


Control 

35 

37 

0 

9.4 

2.8 


0 

Started 











5 





5 min 

41 

36 

0 

8.1 

5.2 


13 


55 



13 min 

57 

32 

0 

10.7 

4.7 


21 



41.4 


21 min 

57 

33 

0 

11.2 

6.9 


23 

Stopped 



+ 







930 

Control 



36.9 


Control 

49 

34 

0.1 

4.3 

4.0 


0 

Started 











5 





5 min 

66 

27 

17.9 

6.4 

3.3 


8 


>60 



8 min 

65 

28 

20.2 

5.5 

4.7 


11 



39.1 


11 min 

62 

28 

23.8 

6.1 

5.3 


17 

Stopped^ 



+ 







929 

Control 



37.2 


Control 

49 

34 

0.3 

6.3 

3.9 


0 

Started | 










3 


1 



3 min 

57 

29 

26.1 

7.0 

4.8 


9 


^75 



9 min 

42 

37 

31.8 

5.7 

6.1 


13 


1 

44.1 


13 min 

39 

34 

35.8 

7.9 

8.2 


14 

Stopped] 

1 


+ 







922 

Control 



37.9 


Control 

42 

35 

0.2 

8.8 

3.1 


0 

Started 1 











3 

1 

1 



3 min 

47 

30 

22.0 

8.9 

5.8 


7 

1 

[75 



7 min 

47 

30 

29.5 

12.6 

6.4 


10 





10 min 

43 

29 

33.5 

7.9 

5.8 


15 

Stopped] 

I 

39.3 

+ 

15 min 

45 

30 

31.4 

8.0 

6.8 

934 

Control 



34.6* 


Control 

41 

35 

0.1 

5.6 

3.1 


0 

Started ] 

^75 










25 

Stopped J 

43.5* 

+ 

25 min 

40 

34 

31.9 

6.5 

6.9 


* Right heart temperature. 


est potassium concentration observed in the erythro- 
cytes in control samples of blood from these animals 
was 9.4 milliequiv/1, in contrast to the pig, whose 
erythrocyte concentrations ranged between 106 and 
145 milliequiv/1. The greatest potassium increase 
that occurred in the plasma of the dogs that died as 
a result of cutaneous exposure to heat was from 3.9 to 
8.2 milliequiv/1. 

The increments to the plasma potassium that were 
observed in these animals could not be accounted for 
by loss of potassium from the erythrocytes. The po- 
tassium content of the red blood cells of the dogs 
characteristically rose during exposure in contrast to 
the loss of potassium that occurred from the erythro- 
cytes of the pig. As in the case of the pig, there was 
severe intravascular hemolysis in animals exposed at 
75 C until death occurred. 

It can be inferred, therefore, that the development 
of a potentially fatal level of hyperpotassemia fol- 
lowing cutaneous exposure to heat results from the 
rapid release of potassium from thermally injured 
red blood cells and that a high erythrocyte content 
of potassium is essential to its occurrence. 


17.10.4 In Vitro Effects of Heat on 
Pig’s Blood 

It was thought that more precise information re- 
garding the reciprocal relationships of temperature, 
time, and the release of potassium from erythrocytes 
could be obtained by heating samples of pig’s blood 
in vitro. 

Heart’s blood was collected from normal pigs by 
cardiac puncture in a heparinized syringe, where it 
was mixed and then discharged into heparinized 
glass-stoppered vials. One vial was kept at room 
temperature as a control; the others were strapped 
to a mechanical mixer and immersed in a constant 
temperature bath. Exposure temperatures ranged be- 
tween 44 and 63 C; during exposure the blood was 
mechanically decanted from one end of the vial to 
the other at a rate of six times per minute. It re- 
quired approximately 2 minutes for the temperature 
of the blood to reach that of the water bath. As soon 
as a sample was removed from the water bath, it was 
immediately cooled in ice water and analyzed. 

It is apparent that there was a progressive increase 
in the rate at which potassium passed out of the 


SECRET 


HYPERPOTASSE3IIA CAUSED BY EXPOSURE TO HEAT 


367 


Table 22. In vitro effects of heat on pig’s blood. 

Potassium in plasma — milliequiv/1 


Speci- 

men 

Temp 

C 

Time 

in 

minutes 

Volume 

packed 

cells 

Hemoglobin 
in cells 
g/100 ml 

Hemoglobin 
in plasma 
% hemolysis 

Potassium 
in red cells 
milliequiv/1 

Total 

Change 

Increment Increment 
from from 

hemolysis leakage 

1-947 

Control 

Control 

30 

34 

0.1 

105 

3.2 





40 

15 

30 

34 

0.1 

113* 

3.5 

+0.3 


0.3 



30 

30 

32 

0.3 

114* 

3.5 

+0.3 

0.1 

0.2 



60 

30 

34 

0.1 

102 

3.8 

+0.6 


0.6 

2-949 

Control 

Control 

32 

33 

0 

99 

3.2 



. . . 


44 

15 

31 

33 

0.1 

107* 

3.9 

+0.7 


0.7 



30 

31 

34 

0.1 

102* 

4.0 

+0.8 


0.8 



60 

31 

33 

0.3 

97 

4.8 

+ 1.6 

0.1 

1.5 

3-949 

Control 

Control 

31 

34 

0 

104 

4.6 





48 

15 

32 

31 

0.1 

101 

7.5 

+2.9 


2.9 



30 

32 

32 

0.1 

90 

9.2 

+4.6 


4.6 



60 

32 

29 

0.4 

90 

11.0 

+6.4 

0.1 

6.3 

4-950 

Control 

Control 

33 

32 

0.0 

109 

4.3 





51 

15 

35 

31 

0.8 

96 

10.2 

+5.9 

0.4 

5.5 



30 

34 

34 

0.5 

98 

11.8 

+7.5 

0.2 

7.3 



60 

36 

31 

0.7 

92 

10.7 

+6.4 

0.4 

6.0 

5-950 

Control 

Control 

34 

35 

0.1 

120 

4.2 





52 

15 

35 

34 

0.8 

103 

10.0 

+5.8 

0.5 

5.3 



30 

35 

32 

2.7 

101 

10.4 

+6.2 

1.5 

4.7 



60 

36 

32 

2.7 

100 

10.9 

+6.7 

1.6 

5.1 

6-947 

Control 

Control 

31 

33 

0.1 

109 

4.2 





55 

15 

40 

28 

1.3 

85 

7.5 

+3.3 

0.7 

2.6 



30 

37 

30 

5.7 

87 

12.1 

+7.9 

3.0 

4.9 



60 

37 

30 

9.6 

71 

18.5 

+ 14.3 

4.4 

9.9 

7-1052 

Control 

Control 

38 

33 

0.0 

119 

3.6 





60 

5 

48 

28 

1.4 

83 

12.6 

+9.0 

1.2 

7.8 

8-1052 

Control 

Control 

36 

35 

0.1 

121 

4.1 





61 

5 

45 

28 

3.5 

76 

20.8 

+ 16.7 

2.4 

14.3 

9-1052 

Control 

Control 

34 

36 

0.0 

122 

3.9 



. . . 


62 

5 

33 

34 

11.7 

69 

30.8 

+26.9 

4.5 

22.4 

10-1052 

Control 

Control 

36 

36 

0.1 

121 

4.1 





63 

5 

26 

34 

31.6 

58 

40.2 

+36.1 

9.6 

26.5 


* These values must be due to analytical errors. 


erythrocytes and into the plasma of the blood as its 
temperature was raised (Table 22). The amounts of 
the plasma increment at the end of 1 hour’s exposure 
at 40, 44, 48, 51, 52, and 55 C were respectively 0.6, 
1.6, 6.4, 6.4, 6.7, and 14.3 milliequiv/1. At the lower 
temperatures (51 C and under), the increments were 
due almost entirely to leakage from intact cells. At 
the end of 30 minutes of exposure at 52 and 55 C, 
the proportion of the plasma increment contributed 
by hemolysis was 24 and 38 per cent, respectively. 

Unequivocal evidence of swelling of erythrocytes 
was first observed at 55 C, although there may have 
been some swelling in all specimens exposed for more 
than 30 minutes at 48 C and higher. 

The rate of change in the blood was much more 
rapid during exposures at 60 C and higher. In these 
experiments the blood remained in the bath for only 
5 minutes and the actual time during which it was at 
the temperature of the water was approximately 
3 minutes. The rise in plasma potassium after such 


brief periods at 60, 61, 62, and 63 C was, respectively, 
9.0, 16.7, 26.9, and 36.1 milliequiv/1. The blood was 
totally hemolyzed at 65 C. 

Not until blood was heated at 60 or higher in a test 
tube were the observed increases in plasma potas- 
sium comparable with those that occurred in living 
pigs after cutaneous exposures at 75 C. This is not to 
imply that the effects of hyperthermia on blood in a 
test tube are necessarily similar to those effects in a 
living animal. Attention has already been called to 
the fact that asphyxia without rise in temperature 
may cause hyperpotassemia in a living animal. Al- 
though the mean temperature of the blood of a living 
pig is never raised to 60 C, most or all of its blood 
may in the course of its circulation through the over- 
heated dermis be brought to a much higher temper- 
ature than would be recorded by a rectal thermom- 
eter or intracardiac thermocouple. It will be recalled 
from the calculations made in Section 17.3 that the 
superficial portion of the dermis of a living pig 


SECRET 


368 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


reaches a temperature of 60 C within a second after 
the surface of the skin has been brought to 75 C. It 
would appear quite possible then that the temper- 
ature of most or all of the blood of an animal that 
had received an extensive cutaneous exposure to 
water at 75 C for as long as 5 minutes would be 
raised briefly during its passage through the sub- 
cutaneous tissue to the neighborhood of 60 C. 

Not until the temperature of the bath was raised 
to 62 C did a 5-minute exposure of blood in a test 
tube result in hemolysis comparable with that ob- 
served in living pigs exposed at 75 C. 

Attention has already been directed to the fact 
that unequivocal swelling of erythrocytes was first 
observed in a test tube after a 15-minute exposure 
at 55 C. So far as could be judged by the hemoglobin- 
hematocrit ratios, swelling of erythrocytes continued 
through 61 C, beyond which it was not observed. 

17 . 10.5 Summary 

These experiments have established that severe 
and extensive cutaneous burning may result in a 
rapid rise in plasma potassium to levels ordinarily 
considered incompatible with life. Such levels are 
obtained when a large proportion of body surface is 
maintained at 75 C for more than a few minutes. 
That lower surface temperatures may also be re- 
sponsible for fatal hyperthermia is suggested by the 
fact that potassium is released rapidly from blood 
cells in vitro at temperatures of 60 C or over. In part 
because of the slowness with which potassium is re- 
leased at lower temperatures and in part because of 
the rapidity with which excess potassium leaves the 
blood stream, it is not likely that thermal exposures 
of insufficient intensity to cause severe cutaneous 
burning could cause sufficient damage to the erythro- 
cytes to produce dangerously high plasma levels. 

In vitro experiments on pig’s blood indicate that 
rapid leakage of potassium from erythrocytes oc- 
curred when its temperature was raised over 60 C 
and that rapid hemolysis occurred when its temper- 
ature was raised above 62 C. Leakage was accom- 
panied by swelling at temperatures ranging between 
55 and 61 C. Above that temperature, so far as could 
be judged by the hemoglobin content of cells, rapid 
release of potassium occurs without cell swelling. 

It was demonstrated that leakage from and lysis 
of red blood cells were the principal sources of the 
potassium increments of plasma. At the lower tem- 
peratures (47 C in vivo and 48 C in vitro) hemolysis 
was negligible. The increase in plasma potassium 


in vivo at these temperatures was due either to dif- 
fusion from extravascular sources or to leakage from 
erythrocytes. It was obvious in the lower- temper- 
ature in vitro experiments that leakage from erythro- 
cytes was the only source of the plasma increment. 
Although leakage alone could be sufficient to account 
for potentially fatal plasma levels (in excess of 
16 milliequiv/1), no such increases were observed 
without accompanying hemolysis. When blood was 
heated in vitro leakage contributed more than hemol- 
ysis to the attainment of such levels. In thermal 
exposures in vivo of sufficient duration and intensity 
to produce comparable levels, hemolysis was the 
more important factor. 

17.11 PHYSIOLOGICAL DISTURBANCES 
FROM EXCESSIVE HEAT ^ 

17 . 11.1 Introduction 

In Section 17.9 of this chapter, attention was called 
to the fact that acute hyperthermic circulatory fail- 
ure in some animals was accompanied by, and un- 
doubtedly contributed to by, large increases in the 
potassium concentration of the plasma. An investi- 
gation of the circumstances in, and the sources from 
which, thermally induced rises in plasma potassium 
occur has been described in Section 17.10. 

Although it appeared that central circulatory fail- 
ure caused by hyperpotassemia was one of the mech- 
anisms responsible for death incident to cutaneous 
exposure to heat, it was apparent that this was not 
the sole cause of death during hyperthermia. The 
following investigations ^ were undertaken for the 
purpose of determining the precise nature of the 
various kinds of circulatory disturbances which may 
result from cutaneous exposure to excessive heat. 

The acute physiological disturbances caused by 
systemic hyperthermia have attracted the attention 
of a number of investigators. Heymans^^ injected 
methylene blue into dogs anesthetized with chloral- 
ose. This produced a gradually mounting rectal tem- 
perature which reached the lethal level of 43.7 to 
44.8 C in 1 to 13^ hours. The heart rate rose gradu- 
ally from 90-120 to 300-330 per minute. At first the 
respirations were deep and rapid (less than 200 per 
minute); after the temperature had risen to 41.5- 
43.5 C they became very shallow and even more 
rapid (over 300 per minute). Systolic pressure rose 
and diastolic pressure fell. Respiration almost always 
failed first, and artificial respiration enabled the 
i By Albert Roos. 


SECRET 


PHYSIOLOGICAL DISTURBANCES FROM EXCESSIVE HEAT 


369 


heart to continue for a longer time. Reflexes per- 
sisted up to the time of respiratory standstill. Uyeno'^^ 
produced hyperthermia in cats, anesthetized with 
urethane, by exposing them to water of 41-42 C or 
to a high environmental air temperature. During the 
30 minutes of exposure the rectal temperature rose 
from 35 to 39 C. There was little increase in heart 
rate, but a pronounced rise in minute-volume out- 
put. Shortly after exposure the respiratory rate in- 
creased to an average of 200 per minute. This breath- 
ing was very shallow (tidal air 2-3 cc per minute) 
and sometimes resulted in a 29 per cent drop in 
arterial oxygen saturation. Cheer placed dogs 
anesthetized with morphine and barbital in a cabinet 
heated by electric light bulbs. In 2 to 3 hours a lethal 
(rectal?) temperature of 43-45 C was reached. The 
heart rate increased progressively until a temperature 
of 42-44 C was reached, when the heart slowed 
rather suddenly. Before this stage electrocardio- 
graphic abnormalities were limited to slight abbrevi- 
ation of the PR interval, slight changes in the QRS 
complex, and inversion of the T wave. The tenninal 
bradycardia was due to the development either of 
nodal rhythm or of various other types of ventricular 
rhythm. Systolic and diastolic pressures remained 
fairly constant up to 41 C, then both dropped, the 
former more than the latter. The respiratory rate 
also increased. Respiratory standstill usually oc- 
curred before cardiac arrest, vagotomy delaying 
respiratory failure. A progressive decrease of the 
blood carbon dioxide was found associated with 
slight alkalosis and rise of oxygen content, which 
were ascribed to the increased pulmonary ventila- 
tion. From the same laboratory, Wiggers and Orias 
reported observations on the effects of short radio 
waves on dogs. The cardiac acceleration, increase in 
rate and depth of the respiration, and primary fail- 
ure of the respiration were identical with the findings 
of Cheer. However, instead of a decrease in blood 
pressure, a rise of systolic and diastolic pressure was 
observed which progressed until death. 

Clinical observations on the effect of hyperthermia 
were made by Ferris et Patients with heat stroke 
whose rectal temperatures varied from 39.9 to 44.0 C 
exhibited a hot dry skin, a normal or elevated sys- 
tolic pressure, which dropped to low levels only in 
the terminal stage, and venous pressures of from 2 to 
12 cm of saline. Their respiratory rate was 28 to 50 
per minute. Of 29 patients (all comatose) whose 
temperatures exceeded 41.5 C, 17 died; all others 
recovered. 


Attempts to analyze the disturbances observed in 
the intact organism by elevating the temperature in 
one organ have been made since 1872. Fick heated 
the blood as it passed through the carotid arteries of 
the dog and noticed marked hyperpnea without 
change in heart rate or blood pressure. Cyon iso- 
lated the circulation of a dog’s head. Perfusion of the 
head with heated blood produced bradycardia and a 
drop in blood pressure. Kahn warmed the carotid 
arteries of unanesthetized dogs without producing a 
rise in rectal temperature. He observed the develop- 
ment of tachycardia and a moderate rise in blood 
pressure. Moorhouse heated the carotids and simul- 
taneously cooled the jugular veins in dogs. This re- 
sulted in tachycardia, rarely preceded by brady- 
cardia, ascribed respectively to increased sympa- 
thetic and vagal activity. Coincidentally, tachypnea 
and peripheral vasodilatation were observed. Hey- 
mans and Ladon severed all connections except the 
vagal nerves between head and trunk of dogs anes- 
thetized with chloralose. Artificial respiration was 
applied and the circulation in the head maintained 
by connecting it to a donor dog. The sublingual tem- 
perature of the preparation rose to 45 C in 1 3^ hours. 
There was no change in the heart rate which had 
risen to 160 after severance of the cervical cord. The 
head exhibited a progressive and pronounced in- 
crease in respiratory rate which persisted until a 
sublingual temperature of 45 C was reached, when 
the rate rapidly decreased and the reflexes of the 
head, which had been active up to that time, dis- 
appeared. 

The effect of hyperthermia on the heart was in- 
vestigated by Knowlton and Starling,^^ using the 
innervated heart-lung preparation perfused with 
heated blood. From 26 C to approximately 45 C the 
heart rate was a linear function of the blood temper- 
ature, the rate at 45 C being 180 per minute. Above 
this temperature marked slowing occurred and the 
heart soon stopped. Arrhythmias occurred above 
40 C. 

To summarize these data, it can be said that in the 
dog the highest rectal temperature compatible with 
life lies between 43 and 45 C, when this temperature 
is reached in 1 to 3 hours. Respiratory failure often 
seems to precede circulatory failure. Tachypnea, 
tachycardia, and peripheral vasodilatation seem to 
be, in part at least, of cerebral origin. 

The physiological changes of rapidly developing 
hyperthermia leading to death within half an hour 
have not been heretofore studied. As high environ- 


SECRET 


370 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


Table 23. Rectal temperature, arterial pressure, and electrocardiogram of 12 pigs immersed in hot water. 

A — Normal sinus rhythm (normal rate, tachycardia, or bradycardia). 

Normal duration of QRS complex. 

A ' — First or second degree A-V block. Normal duration of QRS complex. 

A" — Complete A-V block. Normal duration of QRS complex. 

B — Slight 1 

BB — Moderate Widening of QRS complex without P wave. 

BBB — Pronounced j 

BBB — Can often be interpreted as ventricular fibrillation. 


Time 

min sec 

Rectal 

temp 

C 

Arterial 
pressure 
(mm Hg) 

ECG 

Time 

min sec 

Rectal 

temp 

C 

Arterial 
pressure 
(mm Hg) 

ECG 

Pig 876 (7.7 kg) 48 C. Died after 26.5 min. 


Pig 897 (16.4 kg) 47 C. Curare. 

Died after 56 min. 

Control 

34.3 

118 

A 

Control 

37.9 

146 


16 


44.0 

66 

A 

24 


43.5 

146 

A * 

24 

30 

45.2 

42 

A 

47 


44.0 

90 

A 

26 

30 

45.7 

76 

BB 

55 

• . 

. . . 

36 

A' 

Pig 875 (6.4 kg) 48-50 C. Died after 35 min. 


Pig 946 (9.5 kg) 47 C for 23 min. 

Curare. Died after 42 min. 

Control 

35.0 

130 

A 

Control 

40.1 

82 

A 

27 

30 

42.2 

64 

A 

17 


43.0 

120 

A 

29 


42.8 

64 

A 

26 

* , 

44.4 

40 

A 

34 

15 

43.7 

26 

A 

34 

30 

44.6 

26 

A 

Pig 878 (12.0 kg) 47 C. Died after 50 min. 


Pig 944 (10.4 kg) 47 C for 25 min. Died after 99 min. 

Control 

• • • 

110 

A 

Control 

38.1 

108 

A 

29 


• • • 

70 

A 

14 

, * 

43.5 

120 

A 

37 

20 

• • • 

50 

A 

26 

* * 

45.4 

100 

A 

49 

30 

44.9 

30 

A 

37 

. . 

44.1 

90 

A 

Pig 879 (11.8 kg) 44-47 C. Died after 106.5 min. 


Pig 867 (7.3 kg) 

64-65 C. Died after 15 min. 


Control 

36.8 

106 

A 

Control 

• • • 

146 

A 

33 

. , 

43.1 

54 

A 

5 

30 

. . . 

72 

A 

Out of hot bath* from 33.5 to 48.5 min. 


10 

30 

• • . 

72 

A 

49 

53 

42.0 

116 

• • • 

15 


46.0 

12 

BB 

79 

30 

44.1 

86 

A 

Pig 872 (7.3 kg) 

64-65 C. Died after 1 1 min. 


105 

. . 

44.5 

14 

A 

Control 


150 

A 

Pig 895 (18.0 kg) 49 C. Curare. Died after 32 min. 

7 

. . 

• . . 

50 

A 

Control 

37.8 

148 

A 

10 

30 

. . • 

50 

BB 

15 


41.9 

172 

A 

10 

45 

. . • 

40 

BBB 

25 

30 

43.7 

76 

A 

Pig 871 (9.1 kg) 

70-73 C. Died after 12 min. 


31 

30 

44.0 

10 

A't 

Control 


100 


Pig 943 (8.3 kg) 47 C. Curare. Died after 36 min. 


5 

30 

• • « 

74 

A 

Control 

37.7 

126 

A 

6 

10 

• • • 

74 

BB 

17 


42.6 

126 

A 

9 

30 

• • • 

54 

BBB 

29 


44.5 

136 

A 

12 


44.5 

24 

BBB 


* Skin temperature lowered by exposure to cool water between two episodes of cutaneous hyperthermia, 
t Occasional ventricular extra-systole. 


mental temperatures are needed for such experi- 
ments, the results are necessarily complicated by the 
damaging effect of heat on the skin directly. More- 
over, these high temperatures will produce damage 
to the red blood cells that are circulating in the small 
vessels of skin and underlying tissues. 

17.11.2 Experimental Procedure 
Young pigs weighing from 6.4 to 18 kg and adult 
dogs weighing from 7.4 to 8.5 kg were used as ex- 
perimental animals. They were anesthetized with 
pentobarbital sodium (32 mg/kg intraperitoneally), 
shaved, and tied to a wooden -animal board. This 


was lowered into a galvanized iron tank (92x46x41 
cm). The head of the board rested on a metal bar 
in the tank, so that it was slightly higher than the 
foot. A similar tank, placed on a high table, partly 
projected over the former. This tank was filled with 
water steam-heated to the desired temperature. In 
the bottom of the projecting part was a circular 
opening 13 cm in diameter that could be closed 
with a heavy rubber and metal stopper, resulting 
in full immersion in 8 to 10 seconds. During im- 
mersion, the temperature of the water, which was 
continuously stirred, was kept within narrow limits 
by intermittent introduction of steam. Drainage of 


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PHYSIOLOGICAL DISTURBANCES FROM EXCESSIVE HEAT 


371 


Table 24. Rectal temperature, arterial pressure, electrocardiogram,.hematocrit, and hemoglobin and potassium content 
of plasma and of red blood cells of 15 pigs immersed in hot water. 

A — Normal sinus rhythm (normal rate, tachycardia or bradycardia). 

Normal duration of QRS complex. 

A' — First or second degree A-V block. Normal duration of QRS complex. 

A" — Complete A-V block. Normal duration of QRS complex. 

B — Slight ] 

BB — Moderate > Widening of QRS complex without P wave. 

BBB — Pronounced j 

BBB — Can often be interpreted as ventricular fibrillation. 


Time 
min sec 

Rectal 

temp 

C 

Arterial 

pressure 

K plasma 
ECG milliequiv/1 

Time 
min sec 

Rectal 

temp 

C 

Arterial 

pressure 

ECG 

K plasma 
milliequiv/1 


Pig 877 (7.0 kg) 

47 C. Died after 26 min. 

Pig 905 (12.7 kg) 75 C. Curare. Died after 23 min. 

Control 

34.3 

96 

A 3.8 

Control 

• • • 

94 

A 

4.8 

10 

20 

41.6 

136 

A 6.2 

16 

30 

41.6 

78 

BB 

• • • 

14 

5 

42.5 

112 

A" 6.9 

22 

40 

42.1 

32 

BBB 

17.3 

24 

10 

44.3 

56 

A" 8.2 

Pig 921 (16.8 kg) 75 C. Curare. 

Died after 27 min. 


Pig 923 (13.6 kg] 

47 C. Died after 50 min. 

Control 

• . . 

122 

A 

3.2 

Control 

• • • 

116 

A 3.8 

3 

30 

• > • 

66 

A 

5.1 

13 

15 

• • • 

146 

A 5.5 

8 



58 

BB 

11.6 

22 

30 

• • • 

146 

A 5.5 

18 

. , 

• • • 

36 

B 

11.9 

34 

15 

• « . 

102 

A 6.2 

26 

45 

. • • 

28 

B 

10.2 

42 

. . 

. . . 

56 

A 6.5 

Pig 906 (13.0 kg) 70-75 C. Curare. Died after 70 min. 

46 

33 


66 

A 7.5 

Control 

38.6 

102 

A 

4.0 


Pig 1057 (8.0 kg) 

47 C. Died after 36.5 min. 

10 

50 

41.4 

112 

BBB 

. . . 

Control 

37.0 

• • • 

A 4.4 

16 

35 

42.3 

62 

BB 

17.4 

19 

50 

• • • 

• • • 

A 7.0 

25 

20 

43.0 

92 

BBB 

15.2 

36 

15 

• * • 

• • • 

A 10.2 

44 

35 

44.6 

72 

BB 

13.3 

36 

30 

45.5 

• • • 

0 

46 

40 

44.8 

46 

A 

. . . 


Pig 1056 (7.0 kg) 

47 C. Died after 44.5 min. 

48 

29 

45.0 

46 

BB 

. . . 

Control 

37.8 

• • • 

A 4.7 

65 


46.8 

46 

BBB 


9 

30 

• • • 

• • • 

A 5.9 

Pig 913 (8.2 kg) 75 C for 6.5 min. 

, Died after 

7.5 min. 

15 

7 

• • • 

• • • 

A 7.2 

Control 

38.6 

100 

A 

3.5 

34 


• • • 

• • • 

A 7.1 

2 

25 

37.9 

100 

B 

14.2 

44 

30 

45.5 

• • • 

0 

6 

15 

40.5 

50 

BBB 

17.7 


Pig 910 

(9.5 kg) 72-75 C. Died after 12.5 min. 

7 

45 

40.8 

15 

0 

17.4 

Control 

36.8 

148 

A 3.0 

Pig 919 (9.1 kg) 75 C 

for 5 min. 

Died after 

18 min. 

2 

15 

40.7 

100 

A 19.1 

Control 

37.1 

138 

A 

4.2 

4 

40 

40.7 

86 

BB 18.1 

4 

15 

41.1 

78 . 

BB 

25.5 

7 

20 

41.5 

74 

BBB 24.0 

7 

45 

42.3 

28 

A 

21.4 

13 

52 

43.7 

10 

0 17.3 

10 

10 

43.2 

26 

A 

18.3 


Pig 912 

(10.0 kg) 72-75 C. Died after 14 min. 

14 

. . 

44.2 

30 

B 

17.0 

Control 

36.0 

88 

A 4.1 

16 

45 

44.3 

14 

B 

17.5 

1 

20 

35.4 

154 

A 16.7 

Pig 918 (8.7 kg) 75 C 

for 3 min. 

Died after 

55 min. 

3 

35 

37.0 

98 

BB 

Control 

36.6 

70 

A 

3.7 

5 

7 

37.1 

74 

BB 16.4 

4 

25 

38.7 

56 

A 

11.0 

9 

45 

40.8 

74 

BBB 16.4 

11 


39.7 

62 

A 

9.5 

13 

40 

43.1 

30 

BBB 

17 

5 

40.3 

70 

A 

9.5 


Pig 908 (9.1 kg) 75 C. Died after 13.5 min. 

37 


40.6 

70 

A 

9.4 

Control 

• * • 

96 

A 3.8 

Pig 899 (13.6 kg) 75 C for 1 min. Sacrificed after 77 min. 

3 

40 

. . . 

96 

BB 16.7 

Control 

37.4 

142 

A 

3.6 

8 

55 

. • • 

60 

BBB 18.5 

5 

15 

40.5 

30 

A 

10.2 

11 

10 


52 

BBB 17.1 

16 

5 

40.5 

76 

A 

6.9 


Pig 907 (10.4 kg) 

75 C. Died after 10 min. 

45 

45 

40.3 

76 

A 

4.2 

Control 

37.1 

116 

A 3.5 

76 


39.2 

76 

A 

7.4 



37.3* 

• • • 

« • • • • • 







6 

, , 

39.0 

48 

BBB 









42.7* 

• « • 

• • • • • . 







7 

30 

39.2 

32 

BBB 17.4 









42.5* 


... 








* Right heart temperature. 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


the water and termination of exposure could also be 
accomplished in 8 to 10 seconds. Temperatures rang- 
ing from 44 to 75 C were used. 

Previous to exposure, all animals were heparinized 
(3 mg/kg intravenously). Because of 'spasmodic 
closure of the glottis on immersion, a tracheal can- 
nula was inserted. The carotid pressure was recorded 
with a mercury manometer. The right auricular pres- 
sure was measured by means of a rubber catheter 
introduced into the superior vena cava or right 
auricle by way of the external jugular vein and con- 
nected with a water manometer. The level of the 
right auricle as determined by opening the chest at 
the end of the experiment was taken as the point of 
reference. In pigs the hydrostatic pressure did not 
influence the auricular pressure. In dogs immersion 
resulted in a considerable rise in recorded auricular 
pressure, so that only changes occurring during ex- 
posure could be compared. Pneumograms were ob- 
tained by means of a copper cannula thrust between 
the ribs into the pleural space and connected by 
means of a rubber tube to a writing tambour. In 
other experiments, a tracheal cannula provided with 
a sealed-in side tube connected to the tambour was 
used. Electrocardiograms were taken with an ampli- 
fier type of electrocardiograph. It was only possible 
to take the first standard lead, as the hind legs of the 
animal were under water. In some experiments, cu- 
rarized animals were used and artificial respiration 
was applied throughout the exposure. Intocostrin 
(Squibb) 1 mg/kg diluted with saline was slowly in- 
jected intravenously. The side reactions were limited 
to a short (20 to 30 seconds) period of mild excitation. 
The drug had no effect on the arterial pressure. A 
second smaller dose usually had to be given 20 to 
40 minutes later. A Palmer respiration pump for 
small animals, which allows the air to escape spon- 
taneously on expiration, was used. When venous 
pressures were recorded the animals were immersed 
in such a manner that most of the anterior thorax 
remained above the water level. This was sufficient 
to abolish artifacts produced by the increased re- 
sistance to the inflow of air. Temperatures were re- 
corded with a thermocouple introduced to a depth 
of 7 to 9 cm into the rectum, which had been cleaned 
by repeated enemas. The anus was closed around the 
couple. In three experiments, heart temperatures 
were also recorded by means of a thermocouple in- 
troduced through the external jugular vein into the 
right auricle. In some experiments only initial and 
final rectal and final heart temperatures were meas- 


ured with a sensitive thermometer. In a considerable 
number of animals blood was withdrawn from the 
jugular vein both before and during exposure for the 
determination of the hematocrit and of hemoglobin 
and potassium content of red cells and plasma (Sec- 
tion 17.10). In most instances, immersion was con- 
tinued until death. In some experiments exposure 
was temporarily interrupted, and, in a few cases, im- 
mersion was terminated at a time when the animal 
was still living. 

In addition to these observations, three pigs were 
infused with an isotonic (1.12 per cent) solution of 
KCl. Frequent electrocardiograms (lead I or II) 
were taken. In one of these pigs, the arterial and 
right auricular pressure and respirations were also 
recorded. The latter animal received the solution in 
the subclavian vein, the other two in the jugular 
vein. Blood samples for the determination of potas- 
sium were taken from the carotid artery. 

17.11.3 Results of Experiments 

In Table 23 are shown the results of 12 experiments 
in which pigs were exposed for varying periods of 
time at temperatures ranging between 44 and 73 C. 
Changes in rectal temperature, arterial pressure, and 
electrocardiogram are indicated. 

In Table 24 are shown the results of 15 experiments 
in which pigs were exposed at temperatures ranging 
between 47 and 75 C. The changes that occurred in 
the potassium concentration of the plasma are indi- 
cated in relation to changes in rectal temperature, 
arterial pressure, and electrocardiogram. 

In Table 25 are shown the results of 5 experiments 
in which dogs were exposed for varying periods of 
time at temperatures ranging between 55 and 75 C. 
The changes that occurred in the potassium concen- 
tration of the plasma are indicated in relation to 
changes in rectal temperature, arterial pressure, and 
electrocardiogram . 

In Table 26 are shown the results of 3 experiments 
in which pigs received intravenous infusions of 
isotonic potassium chloride. The changes in the 
plasma concentration of the plasma and the erythro- 
cytes are indicated in relation to changes in hemato- 
crit, arterial pressure, and electrocardiogram. 

Arterial blood pressure. The immediate effect of 
immersion in water of 60-75 C upon the mean ar- 
terial pressure of pigs was a rise which sometimes 
amounted to as much as 140 mm Hg. This rise also 
occurred in curarized animals or when hot water was 


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373 



Figure 34. Plot of thermocouple recordings showing rate of change in rectal and right auricular blood temperatures 
during immersion in low (47 C) and high (75 C) temperature water baths. 

47 C Pig 882 (13.2 kg) 75 C Pig 907 (10.5 kg) 

It may be seen that, although right auricular blood temperature rises rapidly after immersion, there is considerable lag in 
temperature rise in rectum. The higher the temperature of the bath, the greater is the difference between the two. 


splashed on the skin. It was absent at immersion 
temperatures of 45-47 C. 

At temperatures of 44-59 C the blood pressure was 
maintained at or above preimmersion level for 16 to 
26 minutes. It began to fall at variable times during 
exposure, and reached half of the original value in 
17.5-41 minutes. The rectal temperature at this time 
had risen from 34.3-40.1 C to 42-44 C. These ani- 
mals died after 25.5 to 50 minutes with rectal temper- 
atures of 43.9-45.8 C, the heavier pigs surviving 
somewhat longer than the lighter ones. Heart tem- 
peratures were within a few tenths of a degree of 
these values (Figure 34). 

In pigs exposed to water of 60-75 C, the arterial 
pressure was maintained for 1-6 minutes, and reached 
half of its original value in 5.5-11 minutes. The ani- 
mals died after 8-15 minutes with rectal tempera- 
tures varying from 39.4-46.0 C. However, the dis- 
crepancy between heart and rectal temperature often 
was considerable (Figure 34) . 

The possible reversibility of the fall in arterial 
pressure was investigated. Immersion of a pig at 
47 C for 33 minutes produced a fall in blood pressure 
from 104 to 40 mm Hg (Figure 35). Exposure to cool 
water brought the pressure back to its original level 
and lowered the rectal temperature from 43.3 to 
42.0 C. Re-exposure to 47 C again resulted in a fall 
in blood pressure, and death occurred at a rectal 


Table 25. Rectal temperature, arterial pressure, electro- 
cardiogram, hematocrit, and hemoglobin and potassium 
content of plasma and of red blood cells of 5 dogs im- 
mersed in hot water. 

A — Normal sinus rhythm (normal rate, tachycardia or 
bradycardia). Normal duration of QRS complex. 
B — Slight widening of QRS complex without P wave. 


Time 

min sec 

Rectal 

temp 

C 

Arterial 
pressure 
mm Hg 

ECG 

K plasma 
milliequiv/1 

Dog 931 (7.4 kg) 

55 C. Died after 23 min. 


Control 

35.4 

112 

A 

2.8 

5 

10 

37.0 

92 

A 

5.2 

13 

15 

40.6 

58 

A 

4.7 

20 

45 

41.4 

18 

A 

6.9 

Dog 930 (7.5 kg) 

60 C. Died after 16.5 min. 


Control 

36.9 

100 

A 

4.0 

4 

45 

37.4 

86 

A 

3.3 

7 

55 

38.0 

64 

A 

4.7 

10 

40 

39.1 

66 

A 

5.3 

Dog 922 (8.5 kg) 

75 C. Died after 15 min. 


Control 

37.9 

118 

A 

3.1 

2 

55 

37.6 

90 

A 

5.8 

6 

30 

38.4 

68 

A 

6.4 

10 

20 

39.0 

76 

A 

5.8 

15 


39.3 

30 

A 

6.8 

Dog 929 (8.2 kg) 

75 C. Died after 13.5 min. 


Control 

37.2 

130 

A 

3.9 

3 

10 

38.5 

130 

A 

4.8 

8 

30 

42.1 

120 

A 

6.1 

12 

45 

44.1 

74 

B 

8.2 

Dog 934 (7.6 kg) 

75 C. Died after 25 min. 


Control 

34.6* 

148 

A 

3.1 

15 

16 

41.7* 

100 

A 


24 

45 

43.5* 

72 

A 

6.9 


* Right heart temperature. 


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374 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 



Figure 35. Effect of two episodes of cutaneous hyperthermia on pig 879 (11.8 kg) caused' by immersion in water at 
47 C. First period of immersion lasted for 33.5 minutes and is indicated by words “in” and “out” on first and second 
segments of kymograph record. Fifteen minutes after end of first period of hot water immersion and between second and 
third segments of record, animal was immersed again at 47 C and allowed to remain in bath until dead (56.5 minutes). 
Between two episodes of hot water immersion, skin temperature was lowered by exposure to cool water. Total duration 
of experiment was 105 minutes. Upper, middle, and lower tracings on the kymograph record represent respectively 
pneumogram, carotid pressure, and right auricular pressure. The numbers under the electrocardiograms correspond to 
those under the kymograph tracings; C = control period. 


temperature of 44.5 C. In another instance exposure 
to water of 75 C for 1 minute reduced the pressure 
from 140 to 20 mm Hg in 5 minutes. During subse- 
quent exposure to room air the pressure recovered, 
and reached 130 mm Hg after 73 minutes. The ani- 
mal was still alive after more than 2 hours. Exposure 
of one animal to water of 75 C for 5 minutes resulted 
in a fall in blood pressure from 138 to 78 immedi- 
ately after immersion. The pressure continued to 
fall, and the animal died after 18 minutes. 

The arterial pressure in dogs behaved in a way 
comparable with that in pigs at the same tempera- 
ture. Animals immersed at 60-75 C survived for 
13.5-25 minutes. 

Right auricular pressure; Intra-auricular pres- 
sures of pigs before immersion varied from -|-32 to 
— 66 mm H 2 O (average —23 mm H 2 O). In only three 


out of fifteen animals was the pressure in the right 
auricle higher than atmospheric (+13, 20, and 
32 mm H 2 O). In most instances, a slight rise occurred 
following immersion, the control level being regained 
in 0.5 to 3 minutes. In five of the six animals im- 
mersed at 44-49 C, this was followed by a gradual 
drop of 4-20 mm H 2 O. There was no rise in venous 
pressure until 1 or 2 minutes before death. In tii^e 
sixth pig, immersion did not influence the auricular 
pressure (Figure 35). 

In seven of the nine pigs exposed to water of 60- 
75 C, a gradual rise of the right auricular pressure 
was observed, beginning in the middle of or even 
early in exposure and continuing until death. This 
rise amounted to 15-45 mm H 2 O and occurred at a 
time when both arterial pressure and respiration 
were still adequate (Figure 36). In some instances, it 


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PHYSIOLOGICAL DISTURBANCES FROM EXCESSIVE HEAT 


375 



Figure 36. Effect on pig 871 (9.1 kg) of immersion in water bath at 70-73 C for 12 minutes. Upper, middle, and 
lower tracings on kymograph record represent respectively pneumogram, carotid pressure, and right auricular pressure. 
Sequence in which electrocardiograms were taken is indicated. 


was preceded by a fall of 20-30 mm H 2 O which rap- 
idly developed 1-3 minutes after the exposure had 
started. In two animals, this fall was the only change 
in auricular pressure that was observed until 1 min- 
ute before death, when it rapidly rose. 

One pig, exposed for only 1 minute to water of 
75 C, showed an abrupt fall of 40 mm H 2 O. During 
the following 70 minutes the auricular pressure grad- 
ually returned to the preimmersion level, coinci- 
dentally with recovery of the arterial pressure. 

The auricular pressure of four dogs was lower than 
that of the pigs. It ranged from —77 to —108 mm 
H 2 O. Because of hydrostatic effects the auricular 
pressures before and during immersion could not be 
compared. However, neither in the two dogs exposed 
to 75 C nor in those exposed to 55 and 60 C was there 
observed any change in the recorded auricular pres- 
sure during the period of immersion. 

Because of the possible contributions of the type 
or rate of breathing to the observed pressure changes, 
some experiments were performed on curarized pigs. 
Artificial respiration was applied throughout the ex- 
periments. The course of the auricular pressure was 
found to be identical with that of the spontaneously 
breathing animals. At 47-49 C a slow and moderate 


fall was observed; exposure at 75 C resulted in a rise, 
beginning early during exposure. 

Respiration: In agreement with earlier writers it 
was found that a rise in body temperature was asso- 
ciated with a pronounced increase in respiratory 
rate. In the pig the immediate effect of immersion 
was usually a short period of very deep and fairly 
rapid respirations, followed by a variable episode of 
only moderately increased breathing (rate 20-40). 
In the animals exposed to the lower temperature 
range the onset of respiratory rates of 170-200 was 
often sudden, and occurred in the first 10 minutes of 
exposure, at rectal temperatures of 39-41 C. Deep 
gasps interrupted this shallow tachypnea. The ar- 
terial blood maintained its bright red color. The 
tachypnea gradually increased, and rates of 300 were 
not infrequently reached. When the rectal temper- 
ature had mounted to 43-44 C, breathing abruptly 
slowed to 10-40 per minute and became much 
deeper. Additional slowing usually continued until 
death. In the dog, immersion was immediately fol- 
lowed by a tachypnea of 100-150 per minute, which 
gradually increased. Rates over 200 were not en- 
countered. 

It is difficult to estimate whether the respiratory 


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376 


STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


Table 26. Physiological and chemical changes in three pigs intravenously infused with an 
isotonic (1.12%) solution of KCl. 

A — Normal sinus rhythm (normal rate, tachycardia or bradycardia). 

Normal duration of QRS complex. 

B — Slight ] 

BB — Moderate > Widening of QRS complex without P wave. 

BBB — Pronounced J 

BBB — Can often be interpreted as ventricular fibrillation. 


min 

Time 

sec 

Arterial 

pressure 

mm Hg ECG 

K plasma 

Hematocrit milliequiv/1 

K cells 
milliequiv/1 


Pig 901 (14.8 kg). Rate of infusion 0.6 cc/kg/min. 

Died after 50 min. 


Control 


. . A* (lead I) 

36 

4.3 

123 

11 

00 

A* 

36 

9.0 

125 

16 

00 

A* 

37 

9.5 

124 

18 

00 

BB 

38 

11.2 

121 

26 

00 

BBB 

37 

15.5 

132 



Infusion stopped 




26 

10 

0 


• • • 

• • • 

35 

00 

0 


. • • 


36 

00 

A 



. . . 

41 

00 

A 

38 

*8.7 

139 

41 

30 

Infusion started again. 

Rate 0.7 cc/kg/mfn. 


50 

00 

BBB 

35 

17.7 

136 


Pig 911 (8.7 kg). Rate of infusion 0.9 cc/kg/min. Died after 22.5 min. 


Control 

. . 

A (lead II) 

35 

3.2 

127 

11 

00 

At 

34 

8.7 

122 

14 

00 

B 

35 

10.6 

122 

16 

00 

BBB 

35 

12.7 

125 

20 

00 

BBB 

31 

27.0 

. . . 

22 

00 

0 

28 

38.0 

127 


Pig 925 (15.9 kg). Rate of infusion 0.6 cc/kg/min. ' 

Died after 39 min. 


Control 


76 A (lead II) 

33 

3.5 

112 

6 

08 

76 A 

33 

5.7 

117 

12 

40 

76 A 

32 

10.6 

114 

19 

37 

76 At 

34 

12.7 

no 

24 

50 

76 B 

37 

15.7 

109 

35 

18 

24 BBB 

37 

26.1 

111 

* P wave not clearly shown. 

t P wave getting blunt. 


t P wave very flat. 


or the circulatory system failed first in these animals. 
If bradypnea is considered as the first manifestation 
of failing respiration it might be said that the cardio- 
vascular system survived somewhat longer, as judged 
by the presence of an appreciable arterial blood pres- 
sure. However, at least in the beginning of bradyp- 
nea, the pulmonary ventilation certainly was as ade- 
quate as during the control period. If the onset of 
prolonged apnea is considered as the end point of 
adequate respiratory function, both systems failed 
simultaneously. In three animals, artificial respira- 
tion was applied at a time when the arterial pressure 
was still appreciable (80-90 mm Hg), without having 
the slightest effect upon its downward course. More- 
over, the final rectal and heart temperatures of the 
curarized pigs fell well within the range of those of 
spontaneously breathing animals. 


Exposure of pigs to 60-75 C produced an increase 
in respiratory rate which did not exceed 80-90 per 
minute. The breathing remained deep until the 
terminal episode of bradypnea, ending in occasional 
deep gasps. In dogs the respiratory changes were 
essentially the same as those encountered at the 
lower temperatures. 

Electrocardiographic changes: In both pigs and 
dogs, the first change, beginning immediately after 
immersion, consisted of a progressive increase in 
heart rate to levels of 300-350 per minute. Associ- 
ated with this increase, changes occurred in the QRS 
complex, consisting of decrease in amplitude of the 
R wave and deepening of the S wave or vice versa 
with maintenance of the normal QRS interval; and 
inversion of the T wave. The changes in the initial 
ventricular deflection might in part at least be due to 


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PHYSIOLOGICAL DISTURBANCES FROM EXCESSIVE HEAT 


377 



CONTROL 2.5 MtN. 4.2 MIN. 5 MIN. 

3.0 19.1 18.1 



6 MIN. 12 MIN. 

24.0 



13.2 MIN. 

ir.s 


Figure 37. Relationship between plasma potassium level and changes in electrocardiogram (lead 1) during immersion of 
pig 910 (9.5 kg) in water bath at 72-75 C. Plasma potassium values are given in milliequiv/1. Death occurred 12.5 
minutes after beginning of experiment. 


variations in type of breathing with resulting changes 
in the position of the heart. (Harris.^^) They occurred 
only to a minor degree in curarized animals. 

In the pig, the abnormalities following this sinus 
tachycardia varied markedly with the temperature 
of exposure. Of all animals exposed to water at 44- 
50 C (Tables 23 and 24) only one showed appreciable 
widening of the QRS complex and loss of P wave. 
This occurred 1 minute before death. Another animal 
showed disappearance of the P waves. 

The changes in the remaining pigs were limited to 
sinus bradycardia and sinus arrhythmia, which be- 
came most pronounced 2 or 3 minutes before death 
(Figure 35). Occasionally, auriculo ventricular block 
of varying degree was seen during this period. 

In contrast, eleven pigs continuously exposed to 
temperatures of 64-75 C (Tables 23 and 24) all 
showed the gradual development of exceedingly wide 
ventricular complexes with very large T waves, and 
the gradual disappearance of the P wave.^ The gen- 

^ During tachycardia, actual observation of this disap- 
pearance was impossible because of overlapping of P and 
preceding T waves. In these instances, it was assumed that 
the same changes had taken place as in the instances where 


eral shape of these complexes resembled that of the 
original supraventricular ones. Their development 
was usually associated with definite slowing, al- 
though the heart rate remained regular. In some 
cases, the transitional phase consisted of salvos of 
fairly rapid and wide ventricular complexes, which 
interrupted a still-existent sinus bradycardia. In the 
terminal stage, the initial ventricular deflection 
could not be separated from the final one. The elec- 
trocardiogram consisted either of very slow, ex- 
tremely wide ventricular waves, separated from each 
other by isoelectric intervals of 0. 2-1.0 second, or of 
more rapid variations at 160-240 per minute, in 
which one wave merged with the next. The latter 
state might be called ventricular fibrillation (see 
Figures 36 and 37). 

In nine of the eleven pigs, these changes made their 
first appearance early during immersion, at rectal 
temperatures of 37.0 to 41.6 C and at a time when 
the arterial pressure and respiration were still ade- 
quate. In four of these, the blood pressure at the 

the P wave could be followed through a stage of decreasing 
amplitude to disappearance, as subsequent slowing of the 
beat similarly revealed the absence of auricular complexes. 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


time of onset of the wide complexes was actually 
equal to or higher than that before immersion. In 
only two animals were the abnormalities first noticed 
when the pressure had fallen to low levels, and it is 
possible that they would have been demonstrated 
earlier if more electrocardiograms had been taken. 
Exposure for 6.5 and 5 minutes similarly resulted in 
marked widening of the QRS complex, whereas ex- 
posure for 3 minutes and 1 minute did not produce 
deviations other than those at lower temperatures. 

In the dog, the electrocardiographic changes at 
high temperatures were in no way different from 
those encountered at 44-50 C (Table 25). They were 
limited to an increase in rate and to minor changes in 
the ventricular complex. No widening occurred and 
the auricular manifestations remained present until 
the end. 

Chemical Changes. For a complete discussion of the 
effect of temperature on the potassium concentra- 
tion of the plasma, see Section 17.10 of this chapter. 
The potassium concentration of the plasma of fifteen 
pigs in which physiological studies were made are 
shown in Table 24. The initial plasma levels ranged 
between 3.0 and 4.8 milliequiv/1. The potassium con- 
centration of the red blood cells ranged from 113 to 
145 milliequiv/1. The course of these concentrations 
during immersion varied markedly with the tem- 
perature. 

Immersion of four pigs at 47 C produced a gradual 
and sustained rise in plasma potassium. Ten minutes 
exposure resulted in levels of about 6.0 milliequiv/1. 
During the rest of the exposure, the level increased 
by an additional 1 to 4 milliequiv. The highest level 
was 10.2 milliequiv/1 obtained 30 seconds before 
death. 

On the other hand, continuous exposure at 70- 
75 C characteristically resulted in an enormous rise 
in the plasma potassium level. This increase was 
found to take place with surprising rapidity. In five 
pigs, the plasma after 1 to 4 minutes of exposure con- 
tained 14.2 to 25.5 milliequiv/1 of potassium. A sam- 
ple drawn in this period from one curarized pig was 
still essentially normal and the peak observed in this 
animal was only 11.9 milliequiv. Peaks from 16.7 to 
25.5 milliequiv were observed in six pigs during ex- 
posure. Curare did not prevent rises in this range in 
two pigs; however, no early observations were made 
on these animals. In some instances, the potassium 
level fell toward the end. However, it remained 
markedly elevated. 

In some experiments, the exposure was terminated 


before the animal had expired. Immersion for 6.5 and 
5 minutes similarly resulted in a tremendous rise of 
plasma potassium. At the time of death, the level 
was still very high. Immersion for 3- and 1-minute 
periods produced a less pronounced increase; at the 
time of death, the level was only 2-2.5 times the 
normal one. 

17.11.4 Discussion 

These observations show that the physiological dis- 
turbances leading to death in pigs exposed to water 
at 46-50 C are of a different nature from those en- 
countered in animals exposed to temperatures of 
60-75 C. 

In pigs immersed at the lower temperatures, the 
occurrence of a gradual fall in right auricular pres- 
sure followed by a fall in mean arterial pressure indi- 
cates a progressive decrease in venous return to the 
heart. That this decrease, at least during a major 
part of the exposure, was due to an increase in ca- 
pacity of the peripheral vascular bed, rather than to 
loss of intravascular fluid, is evident from the fact 
that the changes in circulatory dynamics were found 
to be reversible to a considerable degree. As the ex- 
posure continued, the detrimental effects of the 
heated blood upon the heart muscle were added to 
the peripheral effects, and both factors undoubtedly 
contributed to the lethal ending. 

It is difficult to say whether cardiovascular failure 
or respiratory insufficiency was the immediate cause 
of death. Profound arterial hypotension and pro- 
nounced bradypnea were usually encountered at the 
same time. It can be said, however, that the mean 
arterial pressure fell considerably before any impair- 
ment in respiratory function was evident. Artificial 
respiration applied at a time when the arterial pres- 
sure was still appreciable had no effect upon its 
downward course. Moreover, curarized pigs did not 
survive longer than spontaneously breathing ani- 
mals; all but one animal died after 25 to 51 minutes 
of continuous immersion. The plasma potassium 
level increased by 66-250 per cent; the highest level 
found was 10.2 milliequiv/1. No profound changes in 
cardiac function, as judged by the electrocardio- 
gram, occurred. As will be shown, plasma potassium 
levels up to 10 milliequiv/1 do not produce significant 
changes in intraventricular conduction. 

At immersion temperatures of 60-75 C, the pigs 
survived for only 8 to 15 minutes. In the middle of 
the exposure, or even earlier, at a time when the 
respiration was still adequate and the mean arterial 


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PHYSIOLOGICAL DISTURBANCES FROM EXCESSIVE HEAT 


379 




Figure 38. Effect of continuous intravenous infusion of 1. 12 percent KCI at the rate of 0.6 kg/min. Upper, middle, and 
lower tracings on kymograph record represent respectively pneumogram, carotid pressure, and right auricular pressure. 
Time in minutes is show n at base of record. Time at w^hich blood samples were taken is indicated by symbols K2, K3, K4, 
and K5. The times at w hich the sequence of electrocardiograms (k to z) were taken are indicated by arrows. See pig 925, 
Table 26, for corresponding potassium levels. 

pressure was still considerable, pronounced changes and electrocardiographic changes in the form of dis- 
in cardiovascular function made their appearance, appearance of the P wave and progressive widening 
They consisted of a rise in right auricular pressure, of the QRS complex, often terminating in ventricular 


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STUDIES OF THERMAL INJURY CUTANEOUS AND SYSTEMIC 


fibrillation. At the same time, the potassium concen- 
tration of the plasma reached values of 16-19 milli- 
equiv/1. This was associated with a striking destruc- 
tion of red blood cells. 

These observations strongly suggest that the hy- 
perpotassemia was responsible for the disturbances 
in cardiac mechanism and for the subsequent myo- 
cardial failure evidenced by the rise in auricular 
pressure. That the damaging effects of a rising plasma 
potassium level first of all manifest themselves in the 
heart is well known. In rabbits and dogs, the infusion 
of a solution of a potassium salt produces a sequence 
of electrocardiographic changes similar to those ob- 
served in pigs during exposure tohigh temperatures.^* 

It was found that an identical sequence of changes 
takes place in infused pigs (Table 26) . In two animals, 
infusion rates were maintained that were likely to 
produce death in approximately the same time as in 
the burned pigs. It is evident that potassium levels 
of less than 10 milliequiv/1 failed to produce either 
changes in the P wave or widening of the QRS com- 
plex, just as was the case in burned pigs. Higher 
levels resulted in a succession of changes which were 
similar in all respects to those observed at high tem- 
peratures (Table 24). In the one animal (Figure 38) 
in which arterial and right auricular pressure and 
respirations were recorded, the auricular pressure 
began to rise 19 minutes after the infusion had 
started. The potassium level was 12.7 milliequiv/1; 
the P waves had begun to flatten 3 minutes before 
and had disappeared. Three minutes later widening 
of the QRS complex began. The arterial pressure 
and respiration remained normal for another 10 
minutes.^ 

That the cardiac changes due to the potassium ion 
are reversible to a remarkable degree is clear from 
experiment 901 (Table 26). The usual succession of 
electrocardiographic changes was observed until, 
some seconds after a potassium level of 15.5 milli- 
equiv/1 had been reached, the string shadow re- 
mained resting. The infusion was stopped. No elec- 
tric or auscultatory evidence of cardiac activity could 
be demonstrated for the following 10 minutes, al- 
though the animal continued to breathe at a very 
slow rate. Then heart action returned and respira- 
tion became more rapid. The electrocardiogram had 
returned to normal. A plasma sample taken 5 min- 


’ The rate of infusion was slow enough so that the rise in 
venous pressure could not be ascribed to the administration 
of the isotonic salt solution per se.^ 


utes thereafter contained 8.7 milliequiv/1 of potas- 
sium. Infusion was started again, the well-known 
changes were again observed, and the pig died with 
a potassium level of 17.7 milliequiv/1. 

The rapidity with which potassium is removed 
from the plasma makes it imperative that the release 
of the ion into the circulation be intensive enough and 
be continued for a sufficiently long time to lead to 
death. This actually occurs in the burned pigs. The 
liberation of potassium often occurred at so rapid a 
rate that there was a lag between the rise in potas- 
sium and the electric changes. Thus, in pig 910 a 
level of 19.0 milliequiv/1 was reached in 2 minutes, 
whereas more than 4 minutes were required to pro- 
duce the typical widening. Animals exposed to high 
temperatures for only 1 or 3 minutes did not release 
sufficient potassium to produce a characteristic effect 
on the heart, whereas exposure for 6.5 minutes was 
adequate in this respect. Exposure to 75 C for 5 min- 
utes resulted in a tremendous rise in potassium and 
in electrocardiographic changes, but even here both 
manifestations diminished in intensity during the 
following 14 minutes. 

Although it is clear that in pigs exposed to high 
(60 to 75 C) temperatures the most striking physi- 
ological disturbances are those which result from the 
release of excessive amounts of potassium, continued 
exposure results in a progressive and generalized rise 
in body temperature which undoubtedly causes dis- 
turbances other than those due to hyperpotassemia. 
Thus, the peripheral and central factors that were 
the cause of death at lower temperatures also come 
into play at these high temperatures. 

In order to evaluate the relative contributions of 
red blood cells and fixed body cells to the increase in 
plasma, potassium experiments were performed on 
dogs (Table 25). Whereas the potassium concentra- 
tion of their fixed cells is similar to that of the pig, 
their red cells contain only small amounts. Immer- 
sion at 75 C resulted in an intense hemolysis, but the 
potassium level did not rise above that encountered 
in pigs at 47 C and electrocardiographic changes 
characteristic of hyperpotassemia were not seen. 

The distribution of the potassium in human blood 
is similar to that in pig’s blood, the potassium con- 
centration of the red cells being approximately 
110 milliequiv/1, that of the plasma approximately 
4-5 milliequiv/1.*^’'^^ High plasma potassium levels 
should therefore be expected in human beings in 
whom a major part of the body surface has been ex- 
posed to high environmental temperatures. Several 


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PHYSIOLOGICAL DISTURBANCES FROM EXCESSIVE HEAT 


381 


minutes of exposure would probably be required to 
result in the very high levels encountered in these 
experiments. It is also probable that, if the immedi- 
ate effects of the exposure were survived, a markedly 
elevated plasma potassium occurring immediately 
following the injury would fall within the next hour. 
It should be remembered, of course, that a rise in 
plasma potassium is a normal post-mortem phe- 
nomenon. 

17.11.5 Summary 

There are two principal mechanisms by which ex- 
posure of the surface of the body to excessive heat 
may cause rapid circulatory failure and death. 

In one, the systemic hyperthermia due to con- 
duction of heat to the interior of the body by way of 
the blood stream leads to a rapid and progressive de- 
cline in blood pressure and failure of circulation due 
to peripheral vascular collapse. 

In the other, the circulatory failure is principally 
central and is due to the effect on the heart of an ex- 
cessively high concentration of potassium in the 
plasma. Central circulatory failure is likely to occur 
when the overheating of the skin and subcutaneous 
tissue is so intense, prolonged, and generalized that 
potassium is released from the erythrocytes with 


such rapidity and in such large amounts as to main- 
tain plasma levels in excess of II milliequiv/1. 

In the case of thermal exposures of low intensity, 
peripheral circulatory failure may occur without suf- 
ficient rise in tissue (and blood) temperature to cause 
a functionally significant ri^e in plasma potassium. 
When a thermal exposure has been of sufficient sever- 
ity to cause fatal hyperpotassemia, the central circu- 
latory effects are likely to be complicated by periph- 
eral vascular collapse. 

It is essential to the development of acute hyper- 
thermic potassium poisoning that the erythrocytes 
have a high original concentration of this element. 
Thus, fatal hyperpotassemia, due to hyperthermia, 
occurs in the pig but not in the dog. Since man and 
pig have similar potassium concentrations in erythro- 
cytes, it is inferred that they are probably similarly 
susceptible to the development of fatal hyperpo- 
tassemia following cutaneous exposures to excessive 
heat. 

Although thermally induced respiratory disturb- 
ances undoubtedly contribute to either type of 
circulatory failure, maintenance of pulmonary ven- 
tilation by artificial respiration does not prevent 
death or cause significant prolongation of the sur- 
vival period. 


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Chapter 18 

MISCELLANEOUS TOXICOLOGICAL STUDIES 

By Birdsey Renshaw 


18.1 INTRODUCTION 

D ivision 9 has carried out, in its laboratories 
operated for toxicological and immunological 
studies on chemical warfare agents, a limited number 
of investigations with materials which were not con- 
sidered for use as war gases but whose toxicological 
properties were for other reasons of interest to the 
Army, Navy, or other National Defense Research 
Committee [NDRC] divisions. In this chapter are 
summarized the results of four such investigations: 
(1) the pathological changes caused by prolonged ex- 
posures to oil screening smokes, (2) the toxic effects 
of gasoline fumes, (3) the toxicity of Salcomine dusts, 
and (4) the hypersensitivity and dermatitis caused 
by hexanitrodiphenylamine and enemy explosives 
containing it. 

18.2 TOXICITY OF OIL SCREENING 
SMOKES 

With the development by NDRC Division 10 of 
generators for the production of oil screening smokes, 
the question arose whether personnel exposed for 
prolonged periods in such smoke clouds (consisting 
of fine droplets of unburned hydrocarbon oils) would 
be subjected to health hazards. Although no informa- 
tion was available concerning the toxicity of oil 
clouds for animals or man, there were on record 
nearly 200 cases of ‘‘lipid pneumonia” attributed to 
aspiration of mineral oil.® Inasmuch as lipid pneu- 
monia may occur whenever an exogenous oil reaches 
the pulmonary tissues and remains for a sufficient 
time to cause irritation, the possibility existed that 
this potentially debilitating condition might result 
from the inhalation of the screening sniokes. At the 
request of the Chemical Warfare Service, an experi- 
ment was performed in which mice were exposed for 
prolonged periods to clouds of atomized lubricating 
oil; ^ the continuing interest of the Service led to the 
extension of the tests to include the exposure of 
monkeys to clouds both of lubricating oil and of fog 
oil standardized for use in the Langmuir- type gener- 
ator. The results of these tests with animals afforded 
no basis for supposing that prolonged exposures of 
military personnel to oil screening smokes in the field 


would be dangerous. By now the actual use of oil 
screening smokes in military operations has been ex- 
tensive and no evidence has been forthcoming that 
health hazards are involved. 

The experiments were performed with animals 
kept for 100 days in a large closed chamber into 
which for 30 minutes of every hour air containing oil 
fog was passed at a rate of 0.8 chamber volume per 
minute. In the experiments with lubricating oil (Penn 
Oil, SAE No. 10), the nominal concentration was 
132 fjLg/\ and the droplets varied in diameter from 
about 0. 3-1.5 m; the mass median diameter was 1.4 /x. 
In the case of fog oil (Texas Company, SGF No. 1 
Oil) the analytical concentration was 65 /xg/1. 

The death rate among the mice exposed to the 
clouds of atomized lubricating oil was not signifi- 
cantly different from that in the normal colony and 
the animals showed no serious pathological changes 
during or at the end of the exposure.^ No free oil was 
ever seen in the alveoli or bronchi, and chemical 
analyses at the end of the 100 days revealed that 
relatively little had accumulated, there being in the 
lungs 1.65 mg per mouse (0.4 per cent of the total 
lung weight). Occasional oil-containing macrophages 
could be seen after the experiment had been in prog- 
ress for a week. These increased in number during 
the first 35 days, after which time almost every 
alveolus contained at least one such cell, but they 
did not become significantly more numerous during 
the subsequent two-thirds of the exposure period. 
The tracheo-bronchial lymph nodes of mice sacri- 
ficed after 3 weeks in the chamber showed accumu- 
lations of oil-containing macrophages, but there was 
no reaction to them. 

These essentially negative results with mice led to 
repetition of the experiments with the Rhesus mon- 
key — a species which, in terms of posture and size 
of respiratory passages, more closely resembles man.'* 
Chemical analyses of the lungs of exposed animals 
revealed a progressive accumulation of oil to a maxi- 
mum of about 10 per cent of the dry weight, or 2 per 
cent of the wet weight, at the end of the 100 days; 
approximately one-half of this accumulation had dis- 
appeared a year after the start of the exposure. 
Microscopic examination revealed some free oil, and 


382 


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TOXICITY OF SALCOMINE DUSTS 


383 


oil-laden macrophages were scattered throughout the 
lung, in the alveoli, subpleurally, and in the bronchial 
and pleural lymphatics. However, little inflammatory 
reaction attributable to the oil occurred, and subse- 
quent to the exposure the fibroplastic reaction to the 
remaining oil was slight. The one conspicuous extra- 
pulmonary effect was loss of hair during the pro- 
longed exposure, and its subsequent regrowth. 

In so far as the animal findings may be applied to 
man, the failure of large amounts of oil to accumulate 
and the absence of severe acute and chronic reactions 
make it improbable that significant pulmonary ef- 
fects would be produced by any exposures likely to 
be encountered. 

The results of exposure to fog oil (SGF No. 1) 
were similar, with one important exception. Six of 
seven monkeys died, apparently of starvation, dur- 
ing or shortly after the termination of the exposure. 
Examination of the stomachs revealed acute or hy- 
pertrophic gastritis and, in those dying after the 
greatest delays, the picture of an adenoma malignum 
superimposed on hyperplastic gastritis. These serious 
pathological changes are believed to have been in- 
duced by carcinogenic agents present in ingested oil ; 
carcinogens have been found in petroleum oils and 
presumptive evidence compatible with their presence 
in SGF No. 1 oil was obtained. Thus, the possibility 
exists that cancer might result from prolonged ex- 
posure to oil smokes. However, it should be noted 
that the monkeys, their surroundings, and their food 
were continually covered with oil, and the animals 
therefore undoubtedly ingested much oil in addition 
to that which they breathed and swallowed. 

18.3 TOXICITY OF GASOLINE FUMES 

Early in 1944 reports were received that among the 
individuals killed in flame thrower attacks upon en- 
closed fortifications were some who had not sus- 
tained severe burns. The Chemical Warfare Service 
was interested in determining the cause of these 
deaths and, as a small part of a larger program, re- 
quested that the effects of short exposures to the 
vapors from unburned flame thrower fuel be de- 
termined. 

As it did not prove feasible to set up toxic concen- 
trations of vapor from thickened flame thrower fuel, 
the tests were limited to experiments with un- 
thickened gasoline compounded to meet Federal 
Specification VVM-564. The gasoline was atomized 
into an airstream which was heated to vaporize the 


droplets before passing to an animal chamber in 
which the air temperature was about 35 C. The 
L(Cj) 5 o’s for 5-minute exposures of mice, rats, and 
guinea pigs were very high, in the order of 300 mg/1 
{Ct = 1,500,000 mg min/m^, analytical). This con- 
centration was somewhat above the saturation value 
at the temperature of the chamber, and a dense cloud 
formed. The mice and rats surviving the exposure 
period remained narcotized for 10 minutes but ap- 
peared normal within one-half hour; no gross patho- 
logical changes were produced. The guinea pigs ex- 
hibited rapid, shallow breathing with forced inspira- 
tions; autopsies revealed bronchospasm and emphy- 
sema. It is probable that the action of the gasoline 
fumes on mice and rats was purely narcotic, and that 
in guinea pigs this action was augmented by broncho- 
spasm. 

The above-mentioned concentration is above the 
upper explosive limit for gasoline and could not be 
built up in the presence of flame. There is no doubt, 
on the other hand, that concentrations of gasoline 
vapor rapidly lethal for man as well as animals can 
be attained in closed spaces in the absence of flame, 
and there is no information as to whether or not 
sensitivity to the vapors is markedly enhanced at 
greatly elevated ambient temperatures. 

18.4 TOXICITY OF SALCOMINE DUSTS 

Early in 1942 the success of NDRC Division 11 
in developing Salcomine ^ oxygen generators for use 
on shipboard and elsewhere led to the need for an 
investigation of the possible industrial hazards which 
might be involved in manufacturing and working 
with this compound. 


® Salicylaldehyde ethylenediimine cobalt, known as Sal- 
comine, has the following structure: 

<Z>-\ 

I Co I 

\ /* \ / 

HC=N N=CH 

I I 

H,C CH 2 

This material has the property of absorbing oxygen (about 
4 per cent by weight) when exposed to air, and of releasing the 
absorbed oxygen when heated. Since this cycle may be re- 
peated many times, it is possible to construct systems employ- 
ing Salcomine for the separation of atmospheric oxygen. For 
details the reader is referred to the Summary Technical 
Report of NDRC Division 11, Section 11.1. No doubt the 
Salcomine samples used in the toxicological studies were 
partially oxygenated. 


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384 


MISCELLANEOUS TOXICOLOGICAL STUDIES 


Preliminary tests ^ revealed that Salcomine dust is 
toxic upon inhalation and clearly indicated the neces- 
sity of taking precautions to protect workers. Mice 
exposed for several hours to the dust at nominal con- 
centrations of 0.4-2. 4 mg/1 (undoubtedly the actual, 
or analytical, concentrations were much lower) fre- 
quently died within 1-6 days. Autopsies revealed 
many pathological changes attributable to the Sal- 
comine : there was generalized degeneration and 
localized necrosis of the epithelium of the trachea 
and principal bronchi; the lungs were hyperemic and, 
particularly in the peripheral portions of the lobules, 
edematous; the thymus gland and lymph nodes con- 
tained fragmenting lymphocytes in moderate num- 
ber; and fat stains revealed fatty changes in the 
liver. 

In 1944 the occurrence of a number of clinical cases 
of poisoning, presumably due to Salcomine dusts, 
occurred ^ and prompted further animal studies.^*^ 


Medical examinations of eleven men ® exposed to small 
amounts of Salcomine dust revealed that the compound pro- 
duced irritation of the eyes, nose, larynx, and bronchi. The 
symptoms, which appeared shortly after exposure and re- 
sembled those of an upper respiratory infection, cleared up 
after removal from exposure. Signs possibly indicative of 
mild systemic effects — muscular aches, nausea, and vomit- 
ing — appeared after latency of 5-24 hours in some of the 
subjects. In general the respiratory symptoms disappeared 
within a day but the digestion was sometimes upset for 3 
days. There may have been some slight cumulative effect, be- 
cause it was reported that chronic exposure led to anemia, 
lack of energy, and need for increased sleep. No permanent 
effects were noted and it was concluded that, with reasonable 
precautions including use of dust respirators, no marked 
industrial hazard was involved. One case with much more 
severe systemic effects has been reported.'^ An emergency 
obliged the subject to work without a mask for a short period 
in an atmosphere laden with Salcomine dust. On the evening 
of the exposure there were no pronounced symptoms other 
than discomfort in breathing, but the following day abdominal 
pains of sufficient severity to require hospitalization and treat- 
ment with morphine developed. The subject had nausea, 
vomiting, and a fever. A tentative diagnosis of acute duode- 
nitis was made and his liver became progressively more en- 
larged and tender. Tests performed 48 hours after admission 
revealed definite liver damage. The liver condition with ac- 
companying jaundice gradually improved but the abdominal 
signs persisted. Penicillin was utilized. An exploratory lapa- 
rotomy 2 months after exposure revealed a retroperitoneal 
abscess in the left lower quadrant; this was removed, as was 
a second similar abscess which formed on the right side 
3 months later. It was suspected that other abscesses were 
present deep in the liver tissue, but none required drainage. 
Definite hardening of the liver due to scar tissue persisted. 
Attending physicians assumed that the inhaled and ingested 
dust was responsible for the acute digestive disturbances 
that followed exposure and led to disease of the liver, duo- 
denum, and retroperitoneal tissues. Compare results of ex- 
perimental animal exposures. 


The results left no doubt that Salcomine is both a 
respiratory and a systemic poison and that precau- 
tions must be taken against the inhalation of its dust. 

A single exposure to a high concentration killed 
guinea pigs immediately and mice after varying 
latencies. The lungs of the guinea pigs were markedly 
distended with air and microscopic examination re- 
vealed that the bronchi and bronchioles were strongly 
constricted. Mice dying soon after such an exposure 
exhibited no visible changes which would account for 
death; those dying after 1 day or more exhibited a 
diffuse pneumonitis, suppurative tracheobronchitis, 
and occasionally jaundice and coagulative necrosis 
of the liver. 

More important from the standpoint of the health 
hazard and for revealing the generalized toxic effects 
of Salcomine are prolonged exposures to low concen- 
trations. Accordingly, animals were exposed for 
1 hour daily in a chamber to air which contained the 
finer particles of Salcomine dust at concentrations in 
the order of 100 jug/1. Three to six such exposures, 
corresponding to a total dosage of about 20,000 
mg min/m^, sufficed to kill approximately one-half of 
the exposed mice and rats; ® rabbits probably were 
not much more resistant, but guinea pigs proved to 
be considerably less sensitive. The mice developed 
a diffuse pneumonitis and tracheobronchitis, paren- 
chymatous degeneration of the renal tubular epi- 
thelium, jaundice, and liquefying coagulative ne- 
crosis of the liver. Autopsies of rats sacrificed daily 
during the exposures revealed a gradually developing 
diffuse pneumonitis and tracheobronchitis; focal 
hepatitis with occasional necrosis also developed and 
was followed by the appearance of intracellular fat; 
parenchymatous degeneration of the renal tubular 
epithelium occurred, followed by the appearance of 
severe fatty changes: and in the duodenum and 
jejunum the epithelial cells of the mucosal glands 
began to show vesiculation, swelling, and many 
mitoses. These changes subsided after the exposures 
were discontinued. Clinical pathological studies on 
rats revealed an increase in the urinary output after 
the first and subsequent exposures, the development 
of a mucoid diarrhea, a rise in hemoglobin and red 
cell count, and a 5 per cent loss in body weight. A 
leucocytosis also developed during the exposures 
and subsided rapidly upon their cessation. 


® To illustrate the toxic potency of the dust it may be noted 
that for 6-hour exposures the L{Ct)so of mustard gas vapor for 
mice is 4,100 mg min/m^, and for rats, 1,500 mg min/m^* 


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HYPERSENSITIVITY CAUSED BY HEXANITRODIPHENYLAMINE 


385 


18.5 HYPERSENSITIVITY AND DERMA- 
TITIS CAUSED BY HEXANITRO- 
DIPHENYLAMINE 

In 1943 the Navy Department reported the occur- 
rence of acute dermatitis in personnel of both British 
and United States armed forces who had come in 
physical contact with enemy explosives containing 
hexanitrodiphenylamine, and requested NDRC to 
investigate the cause of the dermatitis and methods 
for its prevention and treatment. 

A survey revealed numerous statements in the 
literature that hexanitrodiphenylamine is a powerful 
dermatitic agent, but the factual basis for this im- 
pression proved to be weak. Furthermore, dinitro- 
chlorobenzene, a potent dermatitic and sensitizing 
agent for both man and the guinea pig,^^“^^ is em- 
ployed in the manufacture of hexanitrodiphenyla- 
mine, and there is the possibility that this or other 
intermediates or by-products may have been respon- 
sible for those cases of dermatitis which have been 
observed. At du Pont Company plants, which manu- 
factured limited quantities of hexanitrodiphenyla- 
mine in 1918 and 1940, care was taken to avoid ex- 
posure to the substance and no noteworthy or severe 
cases of dermatitis occurred. 

Inasmuch as no samples of enemy explosives 
known to have produced dermatitis were available, 
the investigation ® was confined to studies with a 
highly purified laboratory-prepared sample of hexa- 
nitrodiphenylamine and with a preparation from a 
Japanese torpedo booster. Crystallographic analysis 
revealed the latter to contain about 75 per cent hexa- 
nitrodiphenylamine, about 25 per cent trinitrotoluene 
(TNT), and no dinitrochlorobenzene; if any minor 
constituents were present, they totalled less than 
1 per cent. 


After rigorous applications of both preparations 
had failed to produce irritation or sensitization in 
guinea pigs and swine, tests were carried out on men. 
Neither the pure material nor the Japanese explosive 
proved to be a primary irritant when applied in hot 
weather to skin of the forearm as a saturated solution 
in acetone or as a powder covered by an occlusive 
dressing. In 2 of 29 men treated with the purified 
hexanitrodiphenylamine and in 1 of 31 treated with 
the Japanese explosive, however, ‘‘flareup” derma- 
titis developed about a week after the second of two 
applications. The dermatitis cleared up under simple 
symptomatic treatment within 7-10 days. Patch 
tests later showed that these 3 men had become 
markedly hypersensitive, whereas the 57 other sub- 
jects had not. 

The residue from an incompletely detonated sam- 
ple of hexanitrodiphenylamine was innocuous to 
hypersensitive skin. Prolonged treatment with excess 
potassium sulfide likewise rendered the explosive 
harmless, but treatment of acetone solutions of it 
with sodium hydrosulfite did not alter its ability to 
cause inflammation of hypersensitive skin. 

Although the findings indicated that with gross 
contaminations of large numbers of men, instances of 
skin reaction of varying degree are to be expected, it 
was clear that hexanitrodiphenylamine is not a pri- 
mary skin irritant and that it occupies a low position 
among the skin-sensitizing substances. Practical pre- 
ventive measures were considered to be avoidance of 
unnecessary contact with the substance and, inas- 
much as the reactions are delayed, use of an organic 
solvent and soap and water as soon as possible after 
contamination to remove the substance from the 
skin and from objects with which the skin can come 
in contact. 


^CLASSIFIED 
Dy authoi'ity SiiCJhdtary cf 

OL u lyou 

Defense memo 2 A*tjr«st 1960 

IJBRAKY Or CUNaESSS 

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DECLASSIFIED 
By authority Secretary of 

OCi 2U1960 

Defense memo 2 August 1960 
LIBRARY OF CONGRESS 

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